"Why do you cause so much trouble?" she asked, slightly grinning in the dim light at Evie's resistance to Sam. Every other child had gone to sleep and Anna had been left to ponder the rude comments Evie had thrown at the assistant.
We've already experienced the scene where Evie badmouths Sam. So what? The problem is that you're bringing it up again unnecessarily. Since the reader already knows what happened, they'll have no doubts as to why she's asking the question. I would suggest ending the sentence after "grinning". The rest of the sentence and the whole of the second sentence are mainly irrelevant to the story at this point. Don't let any part of your story live in the past. It only breaks the flow.
As for the rest, it was good, so not much else to comment on.
Hope that helps,
Tony
