i get the impression that OP has bought/ moved to the present house within the last 5 yrs, and had a lot of work done on it, poss by her son.
this son, who is a tradesman and v handy, could poss help with the house painting, even by other contacts and supervising.
i don't get the impression that money, or the cost of this work is the nub of the issue.
it seems to be some dispute between this son, and his sister, who lives at some distance and in some style.
she seems to expect that son will just step in and be responsible for all the helping that mother, OP, needs.
the son presumably feels that his sister ought not to push all this onto him, and she ought to offer some contribution to the effort.
since she cannot get up a ladder, or send others to do so, she should make some financial contribution in lieu of personal exertion.
is that right OP. or something along those lines.
so you are worried about what to accept, from whom, and how much; and trying to keep the ring between son and daughter.
don't know what to advise. except look after yourself.
could you write to them both. pointing out your concerns.
that you are not well, have a serious diagnosis, which may have implications going forward, and just need some security and stability.
i have found that adult children often overlook their parents'
illnesses/ disabilities, or minimise them.
perhaps it's a defence mechanism, or an excuse to expect too much and do too little to help.
try to tell them the realities of your condition. you may have to be quite blunt. or they will say you kept it secret/they didn't realise. victim blaming is common.