I would suggest names that you would use for any children's class.
I worked as a recreation therapist in facilities and camps, and they like to be treated as much as normal as possible.
Some suggestions could be The Explorers, King's Kids, Treasure Seekers, etc. Do you have names for your other groups? Think of one that will fit in with their group names. Hope this helps. It's so nice to hear of a church that wants to incorporate kids with special needs. God Bless. Cindy