It's a shame that your mom is still so troublesome, Tetra.
I dislike large gatherings too where I am expected to mingle.
One good ploy is to walk up to a small group who are talking and just stand there smiling and nodding. If somebody actually makes eye contact, great. If not, move in on another small group and smile and nod.
If it's really horribly boring, or especially if it tempts you to drink, leave early. All you have to do is put in an appearance.
Probably most everybody else is bored, too, and waiting for their discreet opportunity to escape.