Activation locked

https://support.apple.com/en-us/HT201365 There’s a section about forgetting Apple ID and/or password.

See if she can recover the ID/password. Use every email address she can think of.

Apple ID - How to find your Apple    An iCloud e-mail address is an Apple ID.

Apple ID - Find              

For the Apple ID password, enter the Apple (iCloud) ID and click Forgot Password. See if you can get an email option if necessary.

Apple ID - Manage            

Apple ID – Forgot Password