The closest to a Wiki would be a Page which students can edit (and which can be copied between courses keeping their content).
Here are instructions on pages for instructors: How do I create a new page in a course?
And here's a guide she may want to share with students on how to edit pages: How do I edit a course page as a student?
I think the main disadvantage here is that she would need to worry somewhat about formatting, as most students may post questions in the wrong heading/bullet points, and breaking things (for which the page history may be useful).
Alternatively, if you have Collaboration available with Microsoft Office in your instance, she might be able to make an Excel spreadsheet: How do I create a Microsoft Office 365 collaboration.
I don't have Collaborations it in my institutional instance, so I can't test it (and in the FFT instance there's Google Docs, but not Sheets), but I think Excel may be useful here if you can lock the cells that you don't want students to change (such as the answers you've already written).