See if she can recover the ID/password. An iCloud e-mail address is an Apple ID. Use every email address she can think of.
Apple ID - How to find your Apple -
Apple ID - Find -
Other ways to find her Apple ID
She can check to see if she is signed in to the App Store, FaceTime, or Messages on her iPhone, iPad, iPod touch, or Mac, or check to see if she is signed in to iTunes for Windows on a PC. She can also go to iCloud.com or appleid.apple.com and see if her Apple ID prefills on the sign-in screen.
If she forgot the Apple ID (iCloud) password, enter the Apple (iCloud) ID, and click Forgot Password. See if she can get a Rescue or Notification email option if necessary. Link to contact Apple Support at the end of the 2nd article.
Apple ID - Manage
Apple ID – Forgot Password *
If she has 2 Factor Authentication enabled, if she can't recover the password using the steps above, she will need to use Account Recovery. The Recovery Process is an automated process and the length of time it takes can vary a lot. Apple ID Support can only answer her questions. They can't intervene in or speed up the process. The article below has some suggestions to shorten the time the process takes.
Apple ID - Recover your Apple ID with two-factor authentication account recovery. *