I have in my possession the ashes of my biological mother, who died of breast cancer. How can I use them to help in my own battle?

There's an old Roman and pagan tradition that uses something of the ancestors as guardians. They were often on the outside of the dwelling to guard the residents, yet also at cross roads of those less fortunate.

Must note they should be well though of and the shrine blessed yearly. Samhain would be best. You should know why then.

Lookup "Lares"

https://en.m.wikipedia.org/wiki/Lares

Pick something she herself would like.