iPad Alarms are all off but one keeps going off

If I understand correctly, your alarm clock is going off at various times that you have not actually set. I can certainly see how this could become a nuisance. You’re in the right place for a resolution.
First, remove the alarms you currently have set. To do this, follow these steps:

1. Open up your Clock app.
2. Select the Alarm tab.
3. Select Edit in the upper left corner.
4. Tap on the minus sign next to each alarm.
5. Select Done.

After that, restart your iPhone: Restart your iPhone, iPad, or iPod touch. Once your iPhone is restarted, add your alarms again and then give yourself some time to test it out. If the issue persists, go back to your Clock app and select the Bedtime tab. Disable Bedtime and test it out once more.

Check if you have the latest version of iOS on the iPad. If so, this could be the new Bedtime feature that has activated this alarm. See if you have that activated. Go to the Clock, and look along the bottom and you will find Bedtime. It can set an alarm to sound for you to go to bed, and one to get up, based on your daily routing, to help recommend when to go to bed and get up to ensure the best sleep schedule.

Thank you, that was my problem.