#1: what the rest said. Not your money. She could take it to Vegas, or blow it on a Cassanova. As things go, it's not frivolous.
#2: Having said that, is this something your mother can't afford? Will she put her own financial life in jeopardy? If not, see #1.
If she was giving out $100k, I might want to understand if this was an advance on inheritance, or something. But this amount of money is a couple of big trips, which she probably won't do for a while now, anyway.
Good that you are protective of her, if that's it. Inheritance does not need to "come out even."