Does your mum need to carry around 200GB+ of movies and pictures? would she get by fine with a multi-TB drive on the network at home and a smaller laptop hard drive.
There are cloud services that solve this but they have their own set of issues. Many are expensive compared to basic direct/network attached storage, others require photos to be public, others come with dubious guarantees that they will still exist next year.
I get a call from my sister with a 128GB MacBook Air every month or two asking to remind her how to move her baby photos/videos to her external drive. Every time we do it I am surprised how complicated and error prone the process is (we've managed to accidentally permanently delete photos). If anyone has a good recommendation for an alternative to iPhoto (and not cloud based) that understands the concept of archiving photos to a network/usb disk that is not always present I would love to hear them.
It supports both network and impermanently attached usb disks.