Purple, if you are still reading, you sound like a very warm, considerate dil. I hope everything works out for you.
Am I the only one, people, or did anyone else notice that dh has already tried talking to mil? If that didn't help, how would Purple's talking to her do any better?
Also, I don't see where any "door" has been "shut," etc. They are on lc - they see mil on occasion and usually in large groups. She's not getting to see them anywhere near as much as she wants, but she sees them. She would probably like to be with just Purple, dh and baby or even to have baby alone, sometimes. But her behavior and refusal to curb it has made that impossible. Still she's NOT co.
The 10-hour drive is formidable, of course. But, hopefully, she doesn't make it if Purple can't meet up with her or has other activities planned so it's not all dependent on that. But frankly, it's a little ott which is just another example of her overwhelming attitude. In fact, Purple, you may be confusing her by agreeing to meet up some of the time. It would probably be better to decline all these invitations and just stick to seeing her with dh and baby in larger groups. It's not as if you asked her to make that loooong drive. And if she sees that you never accept those "let's do lunch" requests, maybe she'll stop doing that. Better for her as well as you.
I don't think it's a good idea for you to have more contact with mil than dh does in this situation. He may resent it - or he may be counting on it to make up for his lc, and you may come to resent that. It's lovely to be a good dil, but it's more important to be a good dw.