My mom pulls this kind of stuff too. It took me a while to find what works for me. I tell her firmly and with a strong voice that her comments are not appropriate and not welcomed and if she is able to stop being so nasty and treat me like an adult, I will be happy to stay and enjoy the family. Otherwise, I will be on my way. Then I ask her which it will be. Put it back on her to decide.
When she is at my house, I change that last part to "I will have to ask you to leave". It usually shuts he up without engaging her in further conversation. If she keeps it up, I tell the rest of the family and guests goodbye and leave. I have had to do that 2x in the past 5 years. The rest of the time she goes off and pouts. Fine with me!

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