my dad died when i was 11 from a brain tumor so let me tell you fitrst hand what you can do.Nothing,just be the true friend you allways have been.Things could not be worse for your friend right now it is a horrible feeling.Keep your self avalible to her.I'm sorry that you & her or going through such a terrible life experiance,just rember thats what life is sometimes.I hope everything goes well for you both be strong for each other because this is just one of lifes downs sides,you will have more good than bad over all.