What kind of care should I expect to give with chemo treatments for a 77-year-old woman?

My father needs chemo once every three weeks, but my mother cannot be left alone for long lengths of time and he is her primary care giver. I do not know when the worst part of the chemo occurs, and how much my mother can do with her dimentia, should i expect her to be able to do anything at all? She forgets to eat, she is overweight and weak legs. Refuses wheel chairs, and many assistive devices.