Drama !!

Then your mother doesn't have to come. It's not her wedding or her bridal party. Unless your MOH has done something seriously harmful to your mother, she needs to act like an adult or not attend those events.

Your mother doesn't have to come with you, but for her sake you might want to include her in at least one or two things. Planning a wedding is an incredibly emotional and stressful task, and you should only involve people who will uplift and encourage you, and help to enable your vision to come to life. Are there tasks that aren't as emotional or stressful for you that you could include your mother in?

For example,

I only went with my FH to all of our appointments.

When I went dress shopping I only took my mother and my sister, because I wanted people that I had a strong emotional connection and vulnerability with, and who would be as excited and emotional about the experience as I am.

I'll take all of the bridesmaids/female members of FH's family with me when I go for the fitting, so that they aren't left out. That won't be as emotional of an experience so I feel fine having them there.

At the end of the day it's about who can best support you through all of this.

I think the first thing you need to do is sit down with your mom one on one and see what is going on? Maybe she has some misguided opinions about MOH? Or maybe she just wants some special moments to share just the two of you? Go into this conversation genuinely ready to ask her some questions and really hear her answers, and not defensive or confrontational. You don't have to agree with your mom's opinions, but letting her feel like her opinions were actually listened too will be half the battle. This doesn't have to be a harsh conversation, but it may be uncomfortable talking to your mom on the same level and not the "mom-kid" level, but it's important to have

If it seems like there's no changing her mind, then make sure to tell her, kindly but in no uncertain terms, that MOH means a lot to you and is a very important part of your life. Because of this, you want her to participate in X, Y, Z appointments and events. Because your mother is also an important part of your life and you want her at these appointments and events as well, you expect her to be able to act cordially with EVERYONE at the appointments, and focus on you (the bride!) and not on her personal drama. If she feels she cannot do this, then she should not attend.

Now you've heard her side, shared your side, and laid out your expectations clearly. The ball is now in her court to decide how she will act moving forward.

That's unfortunate. Thankfully, my two MOH's love my mom and vice versa. But, even if my mom didn't like someone, she'd tag along and keep her mouth shut. This is all about YOU. Your mom should be able to look past certain things especially to make you happy. If you want your mom involved, sit her down and let her know how important it is to you that they're both cordial and there with you.