Hello, I think the most direct way to do this is to have her log into her account, open her dashboard, and then hit progress. You can then set a custom range of up to two years (you can do this multiple times if needed) and her progress will be there to screenshot.

If you want the school to have access to the account's progress, you could also instruct them to create a teacher account on Khan Academy, create a class, and have her join it through this series of guides. They can then use the activity overview report to see her progress directly and gain more information on it.

Hope this helps :)