grammatical number - User’s/Users’/Users Group

If referring to a Users Group (meaning a group made up of multiple individual users who have some control of the group itself), would you use:

• A: User’s


• B: Users’


• C: Users

I have read the post on the User’s guide but in this case, plural is appropriate since the group does not belong to one individual.

Wikipedia suggests Users’ (or Users) and in my domain, a leading stats software company has a Users Group, though they then use user’s group as part of the description.

What do you think — A, B, or C?