Hey Daniel, not a nice thing to go through!
Fit is everything! At that age if you want some proper protection then look at Carbon helmets- expensive but its the weight issue for such a young child, their head is already heavy compared to the rest of their body, so any added weight up there makes them work much harder.
I kitted my girl up with a Giro Remedy. I increased the cheek and forehead padding by putting extra pads under the original padding. It now fits like a dream and so far no issues. You will need to take her around shops and try them for size. bring extra padding :) and your credit card- but having gone through a+E already how can you not justify some money for your childs safety