All tablets can do pretty much what she wants.
All tablets need an operating system (rather like your PC uses Windows).
There are two main operating system camps at the moment
1) iPad that run the iOS operating system
2) Lots of other tablets that run the Android operating system (supplied by Google)
(There are other tablet operating systems and Microsoft are trying to get in the market with their version of Windows but they are playing catch up).
The Apple iPad is the only tablet that runs iOS, but you do pay a premium for it being an Apple.
Many tablets run Android like the Samsung Galaxy, the Google Nexus and so on.
The Amazon Kindle runs Android, but it has been heavily modified to work closely with the Amazon web site (they want you to download books and music from their web site so they make money that way).
The Tesco Hudl also runs Android.
The important thing with any tablet is to be able to get to the "App Store" where you can download applications. Apple have their own App Store (for Apps that run on iOS) and Google have their App store (for Apps that run on Android).
Some cheap tablets from China DONT give access to the App store so stick to a name brand.
The Kindle Fire HD has been reduced to £119 (costs more for more memory etc) and that would probably be a good stating point for a new user.
Amazon.co.uk User Recommendation