100% approved by our army of gals and we earn nothing from this field report.
Don't buy a cheaper version. The "10-inch sensor trio max" model costs a bit, but it's worth it because each of its features is important to a gal...large size, accurate/adjustable lighting, hands free operation, and so on. This is the only model in Simplehuman's lineup that has all of these features, so if you can swing the price tag, it's really the only one you should consider.
Don't try to buy her any makeup. You might be tempted to throw in some makeup with this mirror (because it would fit with the theme), but that's a bad idea. All you have to do is wrap this mirror and include a card. Besides, you don't know anything about makeup and gals are very particular about what they put on their face, so let her handle that herself. If you want to add in something extra, then get her a gift card to a makeup store (like Ulta or Sephora).