Wow, that is a lot to be dealing with. It sounds awful. Anyone would be anxious and depressed.

One thought I had was to see if there are any social services that could help your mom. I know when my grandmother was in her later years my parents were able to get some assistance with the help of a geriatric social worker. Maybe she would qualify for some sort of financial assistance or transportation to her health care appointments. I found this website that gives some ideas of how to start:

Social Services for the Elderly: How Can I Get Help? | Updated for 2022

As far as your older daughter, I don't know if there is a way you can set a deadline by which she has to move. I am not sure if there is a way to evict her? But, then you would probably be worried about your grandson. There are legal aid services that may be able to help explore your options, but I am not sure how hard it is to qualify for assistance. Law students also hold legal clinics where they help people with legal problems. From quick research it sounds like it is best to contact your local bar association and law schools in the area to see what might be available.

Can you get small safe or put a lock on a cabinet or something where you can keep your cash and credit cards so that your mom doesn't steal them?

Is your 19-year-old in school or working? Does she contribute to the household in any way? She is old enough that she should be doing something to pitch in if she wants to stay living there.