well as I know if you have your stem cell collected at birth, then chances it can be used by your mum. else others are most likely artificial stem cells or other people's stem cells. changes of it usable by a non related person is very very low.

as normal common advise is go for high antioxidant food - garlic broccoli...etc (just do a search on google), and try to avoid red meat as mush as possible. even fish you have to be careful. there are some fish which are actually not good. I am not sure if you are a chinese, malay or indian, but I think most elder person can tell you which fish are ok to take.

not to forget, drink lots of plain water.

and lastly, depends on what religion she believes in, let her get closer to it like some light reading or play some religious sermons or related stuffs for her. that is to help her calm her mood down. an angry and bad mood person kills more cells are some say. so try to keep her mood calm and happy.

I am not an expert in this field but this are some advise I hear a lot. so hopefully it will help you. And good luck to your family.