If it's a simple website, which it probably would be based on the fact she has no experience with websites, packages like dreamweaver would work. She doesn't need a mac.

She would need to work with the designer so they do not design something too complicated for her to update.

Jumping into a local adult ed class on websites may save her many many hours of trial and error.

But I'm also of the camp if you have never done it before, and it's your business, then hire it all out, including the updates.