What are some ways my mom can get relief from caring for my dad?

Dad is 84. Dad is unable to dress or bathe himself; sometimes he makes it to the bathroom on time; falls a lot; his left leg is basically useless due to some stroke activity; is diabetic, down to 120 pounds. Meanwhile, mom is 83, has heart issues but tries to tend to his daily needs. Of course, she's worn out and frustrated. I live 90 miles away so feel that my help is useless though I listen to her as much as possible. Mom has told dad numerous times that they need to talk about a nursing home for him; he is adamantly against it. So mom tries to pick him up when he falls (or calls 9-1-1), dress him, clean him up after accidents. He has home health care folks coming out once or twice a week. We've talked about hiring someone to live in. Is there something we're not thinking of? Some way mom can get relief on a regular basis? She's scared to go to the grocery store for fear he'll fall while she's gone and lay there bleeding until she returns. Any help would be GREATLY appreciated.