I am so sorry to hear that news. I will pray for her and if it be God's will you know she will be in the Lord's arms. I understand what it is like to watch your children and know there is nothing you can do except pray. Praying of course is the best thing you can do.You are absolutely right. My 39 year old daughter is terminal with metastatic cancer. She may have a few months left. We have prayed God would heal her. My church has prayed she would be healed. But that said, she has been God's even while she was forming in her mothers womb. God's will will be done. If He takes her home then that is His will and I will be fine with that because I am not asked to understand His will but to just believe His will is perfect. This doesn't mean I don't suffer, even now, because I do but my faith in His will is firm.
My youngest son has MS, he has just turned 40 and has suffered for years. It affected his sons who were young when he was diagnosed. I felt the pain in my heart when his youngest, who could not understand why his father had changed, said I want my old dad back. I wish he knew God but I know God has him in his hands. He has been blessed with a great wife and sons.
Know my heart is with you and your family. Our love for you is only a taste of how much God loves you and your family.