Hi,
Firstly sorry for your loss.

I would let her go, but maybe organsie someone a little removed to take her out of the service if she gets too restless etc? (a close friend etc) I was recently at a funeral where a young man died. His 4 year old daughter was there, and she was very good, although really didn't understand what was going on. She was just more happy to see photos of her daddy. Also having youth there really helps people with their grief. Young children always manage to cheer people up, just when they need it.