My Mom is an "over-involved" caregiver, stressed out, but there is no "back-up"plan for the patient. Any suggestions?

Hello, my Mom has been caregiving (with in-home aides) for my 99 yr. old grandmother (Stage 7 Alz.) for 4 years. Mom is in poor health and has fallen on the stairs several tims, but refuses to go to her MD; put Grandmom in Respite Care or in an Alz. unit. I am concerned (on several levels), whenever I have broached a need for a "back-up plan", I've bee ignored. Any suggestions?