How can I get in-home health care for my mom?

My mom has Multiple Sclerosis. She's had this disease for the past 25 years, but it just recently started getting worse. She can no longer control her legs and is incapable of moving at all. We currently have a caretaker come by 36 hours/ week (6 hours a day for 6 days). My brother lives with her, but he goes to school and is not always there. My grandfather has been helping out quite a bit by going in the evenings to make sure she's taken care of. She has Medicare & Medicaid and has a very limited income of Disability (around $1400/month which barely covers her rent). My grandpa wants to put her in an assistant living facility, but she really does not want to do that. He can't afford to pay the additional $2000/ month for a caretaker - what type of options do we have? Are there programs that can pay for the in-home health care? What should I do?