Yes, you are not hosting this holiday-Update post 7, 19

[JoyinVirginia]

Sometimes yelling its the only option left, if the person we are talking to refuses to understand communication at normal volume.
I also think not answering the door is good idea.
Another alternative is to tell fil he has to come over early too, and his job is to keep mil out of the kitchen.

[artk2002]

Can you tell her, in a regretful tone of voice, "It's nice of you to want to help, but there won't be enough room; I'm sorry to say that you'll just be in the way."

And feel free to ask her, point-blank, "Do you think we're unable to handle this?" "Do you think I'm a incompetent hostess?"

I'm a big fan of asking questions that help someone see what sort of a message they're sending.

Honestly, she'll show up at two and expect to be entertained if I'm not careful.

Funniest dingity dangity thing!  She arrives at 2:00, finds a note on the door saying "Hi Everyone, We're out for awhile.  See you at five!" --  and nobody's home to let her in!  Imagine that!?   

As long as she doesn't have a key, this one works. As an alternative, can OP come up with a time-consuming (but inessential) errand that she could send her MIL on? "Oh MIL, I realize that our bacon-stretcher is broken. I think they have one at the housewares store in Next-City-Over. Could you be a dear and get one?" (Feel free to substitute a left-handed smoke sifter if you prefer.) Or, send her, legitimately, to get flowers or something like that. Don't tell her in advance about the task -- spring it on her if and only if she shows up and starts causing problems. (Personally, I'd hand her a toothbrush and tell her that the grout in the second bathroom needs scrubbing, but I'm not a very nice person.)

[NotTheNarcissist]

Wow!  If my MIL did this, did not seem to think I was capable of providing proper hospitality and ensuring enough food, I wouldn't be inviting MIL to such events at my home.  Assuming improper hospitality is horribly gauche.

Just wanted to throw in a thank you to Sparksals for saying this. Although I have hosted countless dinners & events over 30 yrs, even to the point people don't want to leave & some stay the night unexpectedly, my SIL has it in her head I am a clueless schoolgirl who can't boil water. So, as you mention, she is no longer invited to our events. Sad but DH actually proposed this as he got tired of his own sister's bossiness & rudeness.

[Venus193]

This sounds depressingly familiar.  Have you posted about this before?

The only way to deal with your MIL is for your husband or you to be direct about this.   For your MIL to ignore your mother is horribly rude and that must be addressed as well.  Also the fact that your MIL has previously sabotaged your food.

If she has a key, change the locks.  If you can get your FIL to help hold her back until your stated invitation time, do that.  He needs to be part of this process.

[learningtofly]

So we survived.  I called MIL and told her what time to come.  Turns out DH had called earlier so she was ok with the time.  She kept grilling me on food-did I have enough of X, should she bring Y, was my mom making Z?  Then she asked if we had a few things necessary for serving the dinner.  She has eaten here before.  I told DH that her treating me like a child was driving me nuts.

Then she decided to go around me and call my mother.  Item Z was essential, but my mom can't eat it do to allergies.  My mom and I were going to make a small batch that she could eat.  Luckily I made it larger as T minus 2 hours MIL decided to not bring her version. She offered to whip up more food.  I had already turned her down and knowing this my mom politely turned her down as well. 

We coordinated oven space for everyone with minimal stress.  My family helped with the serving as they were placed in spots they could easily moved from.  The food was good, my family helped with clean-up and I had the house quiet by the time DD went to bed. 

Now I'm waiting to see if my tablecloth can be saved.

[doodlemor]

I'm so happy that all went well, learningtofly! 

You have shown incredible grace and patience against great odds, as far as your inlaws are concerned.

I wish you success with the tablecloth.  My first line of defense for that sort of thing is oxy spray, by woolite.  I believe it is sold for rugs, but is great on laundry stains.