Hello user4589,
We understand the Lock screen of your mother's iPad is blurry. We're happy to help you both out with this.
It's possible the screen may be blurry because of certain settings on her device. First check to see if Do Not Disturb is enabled. You can check that in Settings > Do Not Disturb. Next see if Bedtime is set. If the device is running iOS 14, you can see if it's turned on by going to Health > Browse > Sleep. The Bedtime schedule would appear under "Your Schedule". When both Bedtime and Do Not Disturb are turned on at the same time it can cause the Lock screen to be blurry.
Respond back if she continues to experience the same thing even without those features turned on.
Thanks for using Apple Support Communities.
Take care.