It sounds like your mother is really expecting to be heavily involved in the raising of your child. As others have said, clear and consistent Boundaries are essential.
You've stated your wives opinion on your mother but not so much of your own. How do you really feel about your mother being around your child? Obviously tough when she's your mother.
The reality is your mother is part of your family and will feel entitled to seeing the kid. I think again it's best to be clear with your mom what your expectations.
Don't make her feel like you are conspiring against her. In my experience people with personality disorders do not respond well to decisions they don't feel they are not involved in the decision. They can't stand not having control. Try and have an pre-planned organic conversation, not an intervention.
Rather than phrasing it "we don't want you too involved- were limiting you to two visits a month" frame it as "we want you involved, so maybe every couple weeks you could stop by". It's not always good to reinforce narcissism but sometimes it can be used to your advantage.
I'd also reccomend a family therapist, preferably one who understands the complexities associated with personality disorders.
Best of luck and congrats on being a parent!
Well, personally, given how my mom feels, I want to let her come visit on a regular basis. However, if she expressed no interest in seeing the baby, and said "maybe I'll come by every few months," I would not be saying "mom please come more, I really want you to be involved." I wouldn't care. My desire to have her come regularly now is a response to her feelings and her desire as it is.
She was coming every two weeks, but it would cause a lot of stress for my wife and I, mainly because I would be upset that they don't get along better. But you have to keep in mind my mom's behavior as well. Last time she was here, my wife was taking the baby to the bedroom for a nap, and my mom got really upset and said that she felt like the baby wanted her to hold her, and that my wife is trying to keep the baby from her. My mom and I went downstairs and argued for over an hour, with her telling me "I know she wanted me to hold her! Your wife is afraid of me having a relationship with her!" etc.
There was no truth in her perception or accusations at all. My wife lets her play with the baby when she's here, no problem. She was getting tired, so she took her for her nap.
For further context (this is the event that really amplified my wife's strong dislike of my mom), a few weeks after the baby was born, my mom and older brother were visiting, and we had been very clear with my mom in advance that at this time, with the baby only a few weeks old, we can only accommodate visitors if they are helpful around the house, and don't just sit around expecting to be treated like guests. She said "Of course. Of course!" So then she's here and she sits for an hour and a half just watching the baby sleep, and so I said "mom you've been here for an hour and a half already and you're sitting here doing nothing." She got extremely upset and said that I was the "rudest son ever" and that my "house is cold" and that her feelings matter, and then threatened to leave and leave us with "no grandma." She was very aggressive, verbally violent, talking about how she's used to grandparents being pampered and taken care of when they're visiting, etc.
My wife was in the other room nursing the baby, seething with rage.
Later my mom was telling my wife things like "I want to work things out between us, even if you hate me, I want you to tell me. Just be brutally honest! Tell me '**** you!' if that's what you want to tell me." So my wife said "okay, well, how about not saying that you're "here to serve us" (my mom's words before visiting) if you don't mean it."
My mom then said that her definition of "serve" is different than my wife's, and chalked the entire thing up to a misunderstanding.
As I said, I completely understand how my wife feels. And we have made progress in getting my mom to behave better, but naturally she is still my wife's least favorite person by a long shot.
Add to this the fact that I have a problem of being too emotionally influenced by my mom (I will be getting therapy for this), and you can more than understand why my wife is very wary of having her around.