Most hospitals say no more then two, but, really, you'll find most hospitals pretty relaxed about that.
I don't know about c-section though, then again, I don't know how attractive that is in terms of spectators anyway.
With my first, I was just going to have my husbandpresent at the actiual delivery, but have my mum in the vicinity-y'know, during the labour, and as soon as the baby was born. But in the end, I had both of the there the whole time (holding a leg each)
after my baby was born, my mum went out to give us a little time.
Not long afterwards, they let her, my dad, my sisters, my sisters's friend (who gave her a lift to the hospital!) in to visit for a while.
My husband's mother (wio is a nut) wanted to be at the birth- wanted to rub my back for me or some caca (shudder) I can just imagine what a pain in the arse she would've been. Nice woman an' all, but seriousy-small doses !!
I quoted the "two only" rule, so it was easy to fob her off gently- I think that is the main purpose of that rule to be honest.