How to comfort my friends? Their 11 year old daughter is in the PICU...?

I am sure after five days at the hospital your friends are exhausted. Offer to come sit with their daughter so they can take a break. If they refuse to leave her bedside offer to sit with them. Bring them healthy foods and clean clothes. If they have pets offer to take them to your house. You get the idea. Try to find a need and fill it. You are a good friend for caring so much.