Start with the software which may specify the OS. Will she be doing any calculations on the notebook or is this just a note taker, Powerpoint prep system?
I work with robotics and computer vision and needed a notebook with a discrete GPU with CUDA support, OpenCV, Caffe. I ended up with what a notebook that is sold as a gaming notebook. I have a Lenovo Y50 and other than Lenovo's recent crapware faux pas have been very pleased with it but there are many good options in this class. A 1TB HD lets me dual boot Windows and Linux and have lots of room for storing datasets and volumes of training images.
If it's just for general computing then many options, many good options.
And as QuietLagoon said, look at what her colleagues are using.