Another vote for Lightroom. As has been said, the organizational features steal the show. When you shoot digital, you shoot a lot. Having some way to work through the hundreds (or thousands) of images from a shoot will help to preserve her sanity.
Keep an eye out for discounts on Newegg and Amazon. I've seen it for less than $100 several times in the past couple months.
And if she's looking to upload to social media, check out Jeffrey Friedl's Lightroom Plugins