she is not able to live alone.
either someone must live with her, or she must move.
if she lacks mental capacity and is deemed to be at risk living there, then steps can be taken by ss.
having a live-in carer is v expensive, and you need cover too.
if the flat is rented, contact the landlord.
has she had an assessment for dementia; there are some advantages in having a diagnosis, but sadly not medical.
it is a progressive incurable condition. some medication can take the more extreme edges off, but not everyone can take it.
it is tricky. does the son recognise that she has dementia. perhaps he cannot face the responsibility of making decisions. so perhaps if someone else contacted ss, that would take the pressure off him a bit ?