If your club agreed to refund his membership, mail him a check along with a letter carefully outlining the circumstances sent certified mail with a receipt.

I say it really doesn’t matter much, other than principle, that the club gets the membership card back. Notify the membership this person has been barred from the club then card won’t do much for him except maybe a discount at the local hobby shop. So if you guys act first and don’t get the card no big deal and this matter can be put into the past much quicker.