Hello, and welcome to iMore!
First, back up all of your photos to your hard drive or some other secure location (I burn mine to disc and keep them deleted from my phone). then log in from a computer to your iCloud account and remove the iPad from your account. You may have to go in to the Apple store and have them transfer it to her for you (I have to do that with my Apple watch that my husband gave me). Then factory reset the device and during the set up have your wife log in with her own Apple ID.
If you need further assistance, feel free to sign up here on the forums for a free account, then reply back here in this thread and we'll see if we can help you get things squared away.
05-15-2018 12:02 PM