W.D.
My daughter was 5 when my mother in law died.. keep it very simple.. sit her down and explain in lay terms, gramma was sick, not sick like a cold, but sick so the dr's can't fix it. she died and is heaven now with God (or whatever your belief is or even leave that out if you wish) and now she is happy and not suffering or in pain. She will be with you in your thoughts and heart and will be watching over you every day. you can talk to her and she will hear you if you want and yes it's ok to be sad and cry.