To be honest I think she can handle LibreOffice. Double-click to open file (can be docx), start typing and click save when done. Open any MS Office file. I really don't get the religuous attachment to MS Office.

I do worry sometimes about fonts. The default Arial replacement should be geometrically idential and thus not lead to issues. TBH I don't know if there are significant rendering issues between LO and MS Office, as I always use PDF. I sometimes upload it to Google Docs to see if it's displayed identically. So far I've never ran into an issue. TBH I think LO is better except for the performance which is okay but not great.

At this point Office programs are commodity. Apple has good options. Google has. And any Linux distro will come with LO. Really a non-issue I think. Even for older people.