How to regain access to iCloud account without security questions

Have a chat with Apple Support directly.

if account recovery or a reactivate request don’t regain access, you’ll probably need a new Apple ID, and some effort to get any associated devices removed from the old Apple ID and added to the new.

If your Apple ID is locked, not active, or disabled - Apple Support

If she is using security questions, I don't think standard account recovery applies in her case. She will have to see if she can now switch to the newer, two factor authentication security method. To cut a long post short, because her account is also inactive, she is best off contacting Apple security about this issue.

This is the most direct way to get to the people helping you with this —> https://getsupport.apple.com/?PGF=PGF63005&category_id=SC0245&symptom_id=23626

or by telephone at one of the numbers in this support article --> Contact Apple for support and service - Apple Support

How to use account recovery when you can’t reset your Apple ID password - Apple Support