How can I make it clear I don't want someone at my wedding?

Hire security? Ask the best man to handle his mom and not share details with her?

Hire security.

I mean that sincerely. Don't extend her an invitation, which you already have planned, but if you are worried about her showing up uninvited, hire security and tell them or see if your venue has security and tell them.

Other options: Have a door checker and require guests to present invitations or have a list of guests and their name has to be on the list.

Edit to add: the above are suggestions that require hiring an outside person. Don't turn this into a "job" for one of your friends or family members.

I'll check to see if they have some sort of security there. It's a hop farm/tasting room and the whole shindig is outdoors kind of out in the middle of nowhere, so I'm not entirely certain if they have someone for that. We'd talk to the friend about it but he's literally the dictionary definition of momma's boy, to the point that once we tell him we don't want her there, he himself might not even attend. I'll definitely check out possible security though. Thank you.

How does she act inappropriately with your fiancé? Is she trying to like have sex with him or is she just acting a little wild and younger than her years??

Her actions would have to be pretty bad to justify not inviting her after she housed him for years when he was homeless. But if they're that bad, you can hire someone to work the door and check names. This will also keep out party crashers.

My dad's mother is in no way invited to my wedding. I have not spoken to her since I was 8 years old and have nothing to do with her (my dad has extremely limited contact with him, like he only has anything to do with her if she's in the hospital on the brink of death). She could die tomorrow and I wouldn't be sad.

I haven't (and am not planning on) sending her an invitation to the wedding. That being said, my dad's siblings still speak to her regularly and I'm sure they have said something about my wedding to her. Although everyone knows she is not invited, I would not be surprised in the least if she tried to show up. I have an off duty police officer that will be security at my wedding. If she shows, she will promptly be escorted off the property.

You can always hire an off duty cop for the night.

Personally, I would hire security

As BonQuiQui said, "SECURITY. SE. CURITY."

We considered hiring security to keep an ex-girlfriend of one of the groomsman out. We each have a restraining order against her so we were very much considering it, but she actually moved and it is no longer an issue. When we were looking at security, it is very reasonable to hire an off duty cop and pay them for the night and it really wasn't too outrageous of a price.

However, if this woman literally took in your FH while he was homeless, you really can't put up with her for one night? We have a handful of people who I would really rather not invite because I really don't like their personalities (like you do with this woman), but they're family. She sounds like your FH's family to me..

Tell the vendor and show them a picture or hire security to escort her out.

I'm grateful that she helped him out for so long when he was in an awful situation, truly I am. I'd have a much easier time dealing with her if she wasn't so hateful towards me and for no reason. She hasn't liked me since day one years ago, and tells her son (the friend) as much. I'd like to think I can tolerate a lot of things, and I generally like most people, but she is, simply put, extremely unpleasant to be around and I don't appreciate the negativity she brings with her. And yes, she has a terrible habit of being too friendly when she's drinking. Her son threw a party at her house about a year ago and she was (pardon me for the tmi) quite grabby below the waist with my fiancé and one of our other friends, trying to neck them, etc. Right in front of me and this other friend's girlfriend.

I like the idea of hiring an off duty officer for the night if the venue doesn't have security. Thank you all for the input, I really appreciate it.

@OP gotcha, a little more inpt makes it very clear you need security!