What is your mom taking exactly? I have Crohn's disease but unfortunately my attempts to treat with MMJ haven't been quite as successful. Since the research is so lacking, you sort of have to come up with a custom protocol. I'd be interested to know what hers is.
I have a friend who uses it to treat Chron's. Before, he was somewhat straight-edge, as I still am.
He learned that cannabis comes under two general categories; one mostly hits "the head", e.g. Makes you really high and behave silly. Another hits the body.
If I remember correctly, the former didn't really help with pain or comfort much; the latter is less popular with recreational users for obvious reasons. At any rate, there's a huge catalog of varieties out there; I would suggest going to forums frequented by other Chrons sufferers or cancer patients and get some specific recommendations.