Help with nephew please...?

My nephew got kicked out of Boy Scouts because he exposed himself and dry-humped another boy. There are other allegations as well that are disturbing. He won't talk to his mom about it so all the information she has given to me is third-person. His best friend was involved and now he won't even talk to him anymore. What can i do to help him or his mom get through this? What are some good lies to explain to his grandparents why he isn't in Boy Scouts anymore? Should i encourage his mom to send him to a psychologist for that kind of behavior or is it normal for an 11 year old? I would appreciate advice if you have any.