Youre kinda "taking her inventory", as dr phil used to say. I agree, she isnt doing things up to standards of a healthy functioning person, but so what? Her family is basically taking care of her, and it seems they appreciate what you do for her.

So she wants the lights off. Its her house, her money. If you have a smartphone, you have a flashlight.

I would LOVE to have a recluse for a roommate. Maybe because i am one also! Maybe she got depressed because of the holiday and thats why she went to the hospital.

Her husband doesnt sound very understanding of her abilities re their son and thats another problem. But it shouldnt be YOUR problem. If something happened to him, you would have no standing to take him to the hospital or anything. I would tell the sister you cant accept that responsibility.

I am like you, or used to be more like you when i was younger - i wanted things done the right way, and really could not tolerate crazy stuff. Luckily i am now retired and able to isolate. But from afar, your situation doesnt look THAT bad? If only you can step outside it to some extent, and they do seem willing to pay you for your extra work there, so i would not "take ADVANTAGE" i.e., excessively, but i would keep careful books. Trustworthy live-in companion would be a good recommendation.