Sorry to hear. I guess you have to respect your mum's wishes. I hope that the chemo sessions she underwent has helped stop/slowed the cancer.
When my auntie was in hospital (she also had cancer), I was reading a magazine. There was an article about a man who had cancer, but he fought cancer by consuming large amounts (I think 10000mg) of vitamin c. I don't recall what type of cancer the guy had. But, maybe it is something worth investigating?