My sister forgot her Apple ID on her iPad and she's 55 and can't remember her password what to do?

Under this circumstance you may have to reset the iPad if you forget both Apple ID and its password.

To reset iPad without Apple ID, you need first put iPad into DFU mode and connect it to your iTunes. Your iTunes will help you to reset your iPad without entering Apple ID easily. Resetting your iPad with this method will result in wiping all the data in your tablet. The following steps will show you how to do that.

Step 1: Open iTunes on your computer and connect your iPad to the computer with a USB cable.
Step 2: After that, turn off you device. Press and hold the Home button for 3 seconds.
Step 3: Put your iPad into DFU mode: Press and hold the Power and Home button for 10 seconds. Then release the power button and keep holding the home button. When you see the Apple logo disappears, you have successfully put your iPad into DFU mode.
Step 4: When iTunes detects that your iPad is in recovery mode, you can restore it now.
Step 5: Click on Restore iPad. Then you will be notified after the reset and your iPad will take a restart.

After resetting your iPad with the guidance mentioned above, you'd better create a new Apple ID and password in time. After resetting iPad, you will get all the data swept from iPad, and you can restore the files from your iPad, iTunes backup or iCloud backup. However, you can't backup iPad to iTunes/iCloud without Apple ID before you reset your iPad . In this case, you need the third-party iOS data recovery software to help you recover lost data from iPad after factory reset without Apple ID.

http://www.leawo.org/tutorial/how-to-reset-iphone-without-apple-id.html