I remember no nudity. But I wouldn't let my child portray an ax-murder victim. Nudity pales in comparison to that (no pun intended).
Children aren’t around when nude scenes are filmed.
In one scene, Jack Nicholson's character enters the haunted Room 237, where he sees a beautiful nude woman in the bath. They embrace. It doesn't end happily.
None of the child actors were part of that scene, so they likely were not even present that day.