Since you didn't say where grandma lives, we can't find out for you if there are any government programs to help pay for house repairs for elderly people. That's the only way I know of not having to pay the full amount for work done on a house. Whoever does the work will charge full rate, but if there is a program then usually you pay the whole bill and the program reimburses you for part of it.
It isn't clear how insurance comes into this. Insurance never pays for maintenance, and it only pays for repairs if the repairs need to be done because, for instance, a tree fell on the house, or some other particular incident caused the damage. It doesn't pay for repairs that are caused by lack of proper maintenance by the homeowner.