Private Social Groups Search Indexing
 

If a user creates a new group and chose to have its content displayed only to group members, will that group be accessible by search engine bots? I mean would the discussions, photos, etc be indexed in Google?

It could be indexed if an unregistered user can see it. A googlebot is just an unregistered user - so they can only see what an unregistered user may see. You could put the pages into your robot.txt file (google it if you don't know what that is) if you don't want them indexed.

So when member tick this option while creating a group
-Users must join to view content

This means that Google bot will not be able to see. right?

I tried robots.txt but that will exclude all the groups unless I have to manually exclude each and every group I don't want to be indexed.

Correct. If an unregistered user cannot see the content, then a spider cannot see the content.