I think you have to have £16k and under in savings not to have to pay the care home fees, otherwise you have to pay and for the sort of more secure care he sounds lives he needs it's about £800 a week. They won't touch the house because your Mum still lives it in. I am am not sure about the pension aspect, have you looked at carers.org or ageconcern.org.uk? They have lots of information about this and info/helplines you can call. But the general upshot is that your Mum should be left with enough to live on.
It's a minefield, just been through this with my Mum and Step FIL who had MS, he died recently I am sad to say.
Sorry for long post, trying to give all details. My DF is 80 and has had Alzheimers for about 4 years. He was a very clever man, always could win quizzes, Trivial Persuit, etc, he was a Bridge champion and even wrote a book. He is at a stage now where he can do crosswords (getting the answers from the back of the book), he can dress and feed himself and go to the loo. My DM, 78, is his only carer and does everything at home; washing, cooking, cleaning etc. I help as much as I can with shopping etc, but also workand have 3 DC. My two brothers do sweet FA to help.
DF spits all the time (only since the Alzheimers), all over the floor, down the side of the chair, in his bed etc, really gross to clear up after and we have resorted to newspapers on the floor and a bath towel next to his bed. My DM is getting very depressed, especially at the spitting. Now, to cap it all, he has started to wet the bed. For my DM, this is a final straw, and yesterday she mentioned him going in a home. We have, as a family suggested this before, but her pride wouldn't let her.
After a long discussion, it would seem one of DM's worries is money. They are well off (£50k in banks etc and £250K house). BUT, almost all the money is in DF name - they were of the old fashioned type where the husband earned the money and the wife never knew how much. We have Power of Attorney now, so ok for day to day living, just take it out of DF account.
If DF goes into a home, he will have to pay. But if his pension is taken, how will DM manage? She only has a very small pension in her own right, nowhere near enough to cover the bills.
Does anyone know how things are worked out so the remaining spouse still has money to live on?