I worked on the district for many years with 'vulnerable' people, one of whom was very similar to this lady. Her house stank, the cats never went outside, they used the small bedroom as a toilet, the place was filthy...but the lady was happy. She had family who regularly visited her, she had a home help, she fed the cats, she fed herself in whatever way she wanted. She also had myself and colleagues regularly visiting her.
When you initially come into contact with people who choose to live this way it is a shock, but it is their choice and they are entitled to live like this if they want. It may not be how you or I would choose to live but that is irrelevant, it's their life and their choice.
If it upsets you then don't go again. She has a home help, if there were major concerns then I'm pretty sure something would already have been done.