I am Nancy and I am a Mental Health expert on the site. I see that "Mind MD" had asked a question, but after several hours - these questions open back up to anyone, so I am going to answer you for the sake of your receiving a timely answer.
It is fairly rare that a child can go through years of school with serious problems without someone at the school intervening. Do you know if she has an IEP or works with the school counselors on her issues?
What does Mom say about the issues you've brought up?
Because nobody can evaluate your grandaughter over the internet - and we would need a lot of information in order to give you a proper diagnosis, my suggestion is that you work with your daughter to get her daughter into a psychologist for an evaluation.
During a full evaluation a Psychologist will talk with Mom and then talk with your grandaughter about what has been going on - he/she will then provide a diagnosis at the end of the session.