I don’t know my ID or password for my old 5c

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 if she is signed in to the App Store, FaceTime, or Messages on her iPhone, iPad, iPod touch, or Mac, or check 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 necessary, if she is the original owner, contact Apple. Apple can remove the ID  if provided the required paperwork to include the original purchase receipt with the serial number on it. 

Request additional support for unlocking your device.    -

You used to be able to take the device, the original purchase receipt with the serial number, and a photo ID to the nearest Apple Store (if it has reopened) and have them remove the ID. This may have changed, so call the store before going to make sure they can help.

Genius Bar Reservation and Apple Support Options - Apple.   -