In credit terms, an authorized user is tantamount to a joint card holder. So, it's not surprising that they're showing up on your credit report. You say the accounts were closed upon your fathers death, but if the accounts were current, you wouldn't be complaining about them being on YOUR credit report. Now, I don't know WHO was responsible for maintaining the accounts, and I'm not here to judge. I'm just saying that's why they're there...
Nonetheless, you can certainly challenge the entry's. If you know they're there, then you have a copy of your credit report or saw it online. When they mailed you the report, they provided a place for you to dispute any incorrect item on your report... I would DO that, and I would DO it again, if it didn't work the first time.