I am pretty sure that information is not able to be queried yet as masna. I am working on that ability but its down the road.
Short of going through each clubs site and checking if they are is about all I know at this point.
OR. just post in the general forum with information so you will get replies.
Title: Looking for 501c3 Clubs
List the details as much as you can have them pm you the address..
If you want to send me an email to president at Masna.org I'll see what I can do to help you out maybe include a little information about the situation