And pray she doesn't want to stay with Windows. My mother learned to use Windows 8 out of spite enough so she doesn't need Linux, but not enough so she can keep her own computer clean (by the way, I need to go back there check how is the new antivirus working, does anybody have good recomendations?).
Personally, I don't bother giving any support to windows users - even family members. First of all, I don't want to waste time learning windows-related stuff, secondly, they know my stance on the matter, and know I won't support non-free software. Finally, they have more motivation to migrate to *nix if they know you'll support them once they do.