I totally get where your coming from! I'm going to say invite your best girlfriends, even though they live far away. If they want to be there, then send them an invite, and if they say no they can't make it - there's no hard feelings because you already don't expect them too. But if they do, then it's a nice surprise for you to spend time with your friends.
As for MIL, I'd just have your husband (or you) remind her that your busy taking birthing classes in the 7th & 8th month on Saturdays - so if something was being planned - you won't be able to make it. Also explain you'd rather have her come out after baby is born rather than have a shower. Sometimes it's easier if your hubby says it because she may listen to him better.