C3 is the Chesapeake Cycling Club, yes. Unless someone has stolen & is using their name for some strange reason, but I doubt that here.
https://www.ridec3.org

They are but 1 club on the DMV peninsula (DelMarVa area), there are at least 2 other clubs that host rides here. I cant comment on this club having never rode with them/in their 2 hosted rides, but I havent heard anything negative about them at least.