Dangerous situation with elderly neighbor

We have these elderly neighbors- they are sisters

The one sister has needed a lot of care but still mobile enough but can’t clean and cook. Her sister has been doing most of the cleaning and cooking and all. They live together

We are in a rental townhome next door.

They talked about their cats from time to time, but we had never been inside

The sister that was healthier now had a massive stroke- will sadly most likely not be coming back home any time soon.

The step daughter was with the one who needs more care and apparently one of the cats needs insulin injected for diabetes. I said of course I would do that.

We go into the house and there is cat litter, throw up, food and hair everywhere… not sure if feces too. It’s clear it hasn’t been properly cleaned for awhile. Step daughter is being rather peculiar and making comments regarding me cleaning up.

I’m texting with her tonight and she said that the one sister that needs more care says she could live their short term on her own. I don’t think this at all… and the state of the house too.

I’m going to go try to clean up tomorrow and change litter box and such… but there needs to be a plan in place.

Step daughter keeps saying she lives over an hr away, works full time, has horses… bunch of comments alluding to that she won’t be able to take care of them.

What would you do?