To remove all that they would have to know here passcode AND her Apple ID AND her password. I think she needs to review her security. If they do know all the above then there is nothing that Apple can provide to recover the device, sorry.
Click on the link and read it to find out what to do "If your iPhone, iPad, or iPod touch is lost or stolen" --> https://support.apple.com/HT201472
- The Find My service is the only recovery feature Apple offers. It MUST be set up before the device is lost. If you did not do that it is too late to do it now and there is no other feature Apple offers that can help you find it other than you try to call it and listen for it ringing.
Click on the link to read how to "Use the Find My app to locate a lost or stolen device" - https://support.apple.com/HT210515
The ability to find a device depends upon which features you selected in:
Set up Find My on your iPhone, Mac, and other devices - https://support.apple.com/HT210400#enablefindmy
Use Find My iPhone to locate your device
https://support.apple.com/guide/iphone/iph09b087eda/12.0/ios/12.0