Lots of great sugggestions, thanks folks...
I ordered a copy of Anticancer and had it shipped to my mom, along with The Cancer Fighting Kitchen cookbook that looks to be paleo/primal (and a copy of my one of my favorite books, The Glass Castle, because hey, just sending cancer books is a downer!)
Neckhammer, I'll do some reading about ketogenic diets and cancer, and do the best I can on that front. If she's nauseous and feeling crappy, I may need to just feed her whatever healthy thing she can handle, though, so I'll see if she's able to handle low/no carb. If not, Jammies, you had a lot of good advice, I'll see if I can maybe get a little ice cream maker and make small batches with raw milk, and keep some potatoes and rice on hand. The tip about small portions was good - I would have never thought of that. Fiercehunter, I'll be sure to stock on on the raw organic coconut oil (I'm pretty sure there's some at her apartment from my last visit) and I'll see about getting some raw grassfed butter.
And Paleobird, I defintely understand your concern about the snake oil cures. I know that it can't be cured with some smoothies and a handful of supplements. And even though I might not choose the radiation/chemo route for myself, that's what she's going to do, and I'm seeing my role as her supporter; I just want to reduce her stress and help her recover from the ravaging effects the treatment will have so her immune system can be functional and strong again, so you don't have to worry or get too upset here.