As for foods, I have found that eating fresh fruits and vegetables, fish and meat help. If you can afford it, eat organic. Don’t eat boxed, canned or frozen foods as it tends to lose most of its nutritional value and vitamins.

I have tried the macrobiotic diet and it wasn’t for me. I personally did not get much out of it, although I have heard from many that have.

I am sorry to hear about your mother. Brain tumors are never easy, regardless of which type you have. I would also recommend, if your mother hasn’t done so already, to seek a 2nd, 3rd, or even 4th opinion before having any type of surgery, chemo or radiation done. Every doctor is different and so are there treatments. It really does make a difference.
References :
Brain tumors upgraded to brain cancer in 2005