Agree with the other ladies. Giving the gift back is awkward. But since he already comes to play at your house, you could recelebrate if you wanted with just the 2 kids. Make 2 cupcakes or something.
But if not, a good thank you note and the goody bag will suffice.
SAHM to Magnolia May (09/10), Luke Russett (04/13) and expecting 11/16. Wife and best friend to my airman.