Mom locked her phone

If your Apple ID is locked or disabled - Apple Support.    

If you have changed your ID or password, have you followed the steps in this article?

What to do after you change your Apple ID or password - Apple Support.      

If necessary, contact Apple ID Support. Based on multiple posts I have read, they may not be willing to help. See the Apple Support articles below for contact information.  

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.

From the Apple Support article below. 

Without proof of your identity via security questions and other carefully selected criteria, Apple Support can't help you reset a password or perform any other actions on your account. These policies are audited and reviewed on a regular basis.

Security and your Apple ID - Apple Support.      

You say it is locked. Is it activation locked. If so,

If you are the original owner: If you have iOS 11 or later and your account is protected with two-factor authentication, use get help with a forgotten passcode or disabled device to recovery your passcode. Otherwise, use forgot your Apple ID or your Apple ID password to recover the needed credential(s.) If you can’t recover the needed credential(s), contact Apple Support and present your original purchase receipt for your device from an authorized Apple seller with the device’s serial number on it. You’ll need a photo ID too. If you can do neither, then the device is useless to you.

If you acquired your device second hand, you usually will need to obtain the needed password from the person that last set it up. If you can’t obtain it, in the rare case your device came activation locked from an authorized Apple seller, then contact Apple Support and present your original purchase receipt for your device with the device’s serial number on it. You’ll need a photo ID too. If you can do neither, then the device is useless to you.

In both cases, you can use the suggested support options provided by Eric Root above. Alternatively, if an Apple Store is open in your area, then you can go there to deal with your problem. In this case, you can make a genius-bar appointment (https://www.apple.com/retail/geniusbar/) if you want.