I'm so sorry, (((tied))). That has to be darn tough for you to try to figure out how best to help her.
What kind of cancer does she have? Has she been sick long? How old is she?
Sorry, so many questions, but just trying to understand your situation a little better. Don't know if I can help, but my Dad had cancer recently (lymphoma).
Bless you for taking care of your step-mom.