First of all I'm sorry to hear about whats happened to your parents. Dealing with one parent passing away and the other being severely ill is HELL. On top of that, you also need to find your "way in life" at the same time. You really are in an unenviable position and one I would not wish on anyone.
With all of that being said, I am not really sure you yourself really know what you want to do. You mention you have an interest in military history, weaponary, militaria etc... but is your interest in this field more "hands on" or is it more academic ? There is nothing wrong with following your passion when it comes to work, heck doing something you actually like/enjoy is a good thing, but you have to figure out a way to make $$ from your passion.
In your case if you have a passion for the "hands on" aspect of firearms/weaponry/militaria then you may want to look into gunsmithing or joining the military. As a gun-smith, especially in the US, you can make good living from it. However to make the big $$ as a gunsmith you probably have to be pretty good at it. Now if at 31 you start training to be a gunsmith you've probably started later than most. While its better to do something late than never expect that for at least a few years your salary is going to be pretty low.
Another option as others have said is to join the military. You could look into going into OCS. The advantage there is if you get accepted and complete OCS and get commissioned, then you have a pretty good starting salary and benefits as a second lieutenant. However your age could be an issue here. I think to attend Army or Marine OCS, the maximum cut off for age is your early 30s. So likely this route is to late for you to take. The advantage here would have been that the Army and Marines are more accepting of candidates with a BA, indeed i think many Army and Marine officers do have BAs. Your other options are the Navy, Airforce or Coastguard. I believe for these branches of the military the cut off age for OCS is higher- like your mid to late 30s. However the issue here is that I believe the Navy and Airforce have a preference for people with B.S. or M.Sc. degrees rather than BAs or MAs. From what I have heard, when it comes to potential officers, they look for people with STEM degrees. But I'm sure there are Naval or Airforce officers that have BAs. If this is the route you want to take you should probably get on this sooner rather than later, as time is really not your friend here at the moment.
If your interest in the military or weapons is more academic i.e military history, then only having a B.A. in this field at 31 was not really the best way to go about it. If you wanted to work in this, then at this point you should have ideally already had your Ph.D. completed or be in the process of doing it. And at the very least you should already have an MA. Preferably from a top 15 university. But mind you becoming a professional historian is not easy nor is it a guarantee of a good job. Even having a Ph.D in your field you would likely need to spend at least several years travelling from community college to community college taking contract/ part time based gigs and hoping you eventually get a position at a good institution. But going this route does offer an opportunity to make a decent living either in academia or working for an intelligence agency but its a process that takes many years. It involves a great deal of hardship to. Its also not a field where just having the academic credentials is enough. Its field that's highly dependent on X factors. Such as having a good relationship with your supervisor, networking well to have as many contacts as possible in different departments across a variety of institutions etc... Getting involved in academic journals and publishing your work in academic journals goes a long way as well. Going to conferences as well is critical.
Correct me if I am wrong but I assume a job like this would interest you greatly (perhaps it would even be your "dream job") :
https://www.cia.gov/careers/jobs/intelligence-scholar/
However, given your present situation and credentials, getting this job is nigh impossible. However if you had an advanced degree in history, published several academic articles or even wrote a scholarly book perhaps on a CIA operation/history, spoke one or more foreign languages, and had teaching experience at the university level then your chances of getting this job would greatly increase. Even with all this, the likelihood of getting this job would still be fairly low, but at least it would be a somewhat realistic goal.
I know a few people who have Ph. Ds, despite the fact that they are all undoubtedly "smart", they have had varying degrees of success in their professional lives.
Now I don't know how it works with the CIA, but CSIS (Canada's CIA) offers internships for students. This is the "easiest" way to get your foot in the door. While getting an internship is not easy it is much easier than getting straight up hired. If you perform well as an intern you have a decent chance of getting a full time position upon graduation. Now if you did an M.A. in political science or history and applied to an internship position with the CIA, that maybe a way to get in, but its far from a guarantee.
However doing all of the above would have been significantly easier while you were living with your parents. Now unfortunately you will probably be forced to take a, what I would call, "road to nowhere" job just to make ends meet. The job at that local museum/historic house is one example. It may help to pay the bills for the time being and allow you to have some food in your belly but that job is probably not a good long term solution. You would probably want to work in some field that will give you a realistic shot at advancement. Yeah America is a rich country but it is also a country of profound inequality. Just look at the difference in median and mean wealth in America :
https://en.wikipedia.org/wiki/List_of_countries_by_wealth_per_adult Yeah being rich in America is great but being poor is no fun. Life in Skid Row or in some other American ghettos is about as bad as life in any Brazilian favela... Don't end up on the wrong side of the fence.
This is why, as others have said, a skilled trade maybe your best long term solution as that is a career path that can lead to a very good income and has a relatively low barrier to entry. However most of them require schooling and at the moment you need to be generating an income to survive.
This is not really my business, but since you posted this on a public forum, I may as well voice this. Do you have any friends or family you could live with, once your parent's house is sold ? Obviously I am not saying that you should be a leech and live off them without paying for rent or anything but just to find someone you know to live with as room-mates ?? Splitting the rent/housing bill is a huge help when you are first starting off, and not to mention that given your present situation, not being alone and having someone to talk to etc.., in my opinion, would greatly benefit you. But all of this requires taking any job you can get at this moment. Also living in an assisted living home requires a lot of $, at least in Canada. You mentioned that "we are in the process of selling my parent's house"- i assume the we refers to your siblings? I also guess the proceeds from selling your parent's house will go towards covering the assisted living costs?
One final thing you might want to consider when it comes to moving is being away from your mom. If you move and as a result you don't get to see your mom much or spend time with her, regardless of her Alzheimer's, and your mom passes this could be something you will severely regret for the rest of your life. One thing to take into account.
