Cape May by Holly Caster. It's a romance with characters your mom's age, so she'll love that. Plus, there's only one or two scenes that would make you feel uncomfortable if you thought about your mom reading it. In other words, it ain't Fifty Shades of Grey. I wouldn't steer you in that direction, believe me.
Yes Please by Amy Poehler. It's a sweet memoir that will make her feel awesome about being a superhero called Mom.