First things first: what does she like to read?
I ask that because it will help me point her to publishers and stores that sell DRM-free ebooks. Here are
my five favorites.
Next: Have her install
Adobe DE, and see if the app will recognize the Sony Reader. If the app does recognize the Sony Reader, then she can buy DRMed ebooks from Kobo, Google, and many other ebookstores. Those books can be loaded on to the Sony Reader using Adobe DE.
BTW, does the thing even still work?