I read recently that a high school student in Rhode Island successfully sued to have a prayer removed from the wall of her school. It was reported that she was baptized in the Catholic Church, but became an atheist after her mother suffered a serious illness when she was ten. She said prayer didn't change anything, and she realized it's all a myth. She was quoted as saying that the prayer made her feel that she didn't belong in her school. The article was unclear, but seemed to imply her mother survived her illness.
I understand feeling angry at God because you think he is not listening, or is not granting your requests. Ten is perhaps a bit young to understand the concept of waiting.
Who is God and who do you want him to be? I don't want to be able to understand, analyze, and predict him. The things she reportedly wanted are the things I reject. I want God to be bigger than anything I can even begin to contemplate because I want to believe their is a purpose even when I cannot see it.
I hope this young lady finds the place she where she belongs. There is joy in sharing the path with someone else.