not sure where you live, but there are usually federal programs, state programs, county programs, and city programs for subsidized/low income housing. there are regional waiting lists and there are also individual complexes that hold the voucher. some, you must apply to each complex individually.
There is also the option of renting a room.
You can work and keep your check, if you make under a certain amount, but sounds like she is not able to work.
Food banks can sometimes give food up to every 2 weeks. there are programs through the USDA. Remeber the butter and cheese of the 80's and 90's? there's a version of that still around that includes many more types of foods, you just have to find an agency that distributes the food. you can start your search here: http://www.fns.usda.gov/fdd/contacts/sdacontacts.htm

your city's senior services department can usually find whatever the person needs, including meals on wheels and legal aid. Sky is the limit. the only tough part is finding the services.