She is probably getting SSI or some kind of social security for her disabilities, too.
SSI is about $700 a month. It's not much at all.
I don't know if she would be eligible for SSD, which is more than that. But since she has apparently never held a job, she most likely is not.
She should be eligible for SSI, SNAP, welfare type income assistance, and Medicaid. There might be other things as well.
I just read some online info about Medicaid assistance for long term care in Pennsylvania and it looks like she'd be eligible for that too.
The info provided is too sparse to really know what was going on. I'm holding out on forming an opinion until more info is provided. For example I would like to see some photos of the 'wooden cage'.
What I have seen in some cases is that the family is not aware of the social programs and assistance that is available for the disabled. So they try to handle it all themselves and get overwhelmed.
I wonder what got the police to check out the house and check on the disable sister to start with. That's not addressed in the articles I've seen.
On the surface it sounds horrible.