Apple ID issues

If you/she are the original owner, contact Apple. Apple can remove the Activation Lock if provided the required paperwork. Either take the device, the original purchase receipt with the serial number, and a photo ID to the nearest Apple Store (if it has reopened)

Genius Bar Reservation and Apple Support Options - Apple.    

or contact Apple ID Support. 

 Apple ID - Official Apple Support.    

Contact Apple for help with Apple ID account security - Apple Support.  (Link doesn’t always load)   

Get Support      Work through the screens to get a chat option. 

Apple Support schedule phone call

https://twitter.com/AppleSupport       People have posted it may take an hour or more to get a response.

Assuming you know her Apple ID/Password, then the most likely explanation for what is happening that someone else's Apple ID is linked to the iPhone. Is that what is happening here, and, thus the phone is activation locked? If so, there is no way the activation lock can be removed because she will lack the needed password: won't be able to contact anyone that can help her (i.e., the prior owner), and won't have a receipt showing legal ownership.