that is very sad...
i work in the aged care industry and would suggest perhaps seeking out some respite for your grandmother... not sure of everyone's stance but sometimes a week in care is enough to give the full time carer a break... do you think he would be open to going into short term care for a week here or there? you can also get alot of services at home, like help with showering etc, shopping..... he would be assessed and then alotted a certain amount of help... the first step is to have him assessed and then go from there (if this is the direction you want to go in, to get extra help for your grandmother)

if you type in commonwealth carers respite centre into google, it should provide you with information.... you might be surprised just what he is entitled to to make life easier on those caring...

good luck