Require some information.

I put my Avast on my moms tablet about 3 months ago to help keep her “safe.” She came into my room to tell me that she has a virus, I scanned it and sure enough there’s a “Trojan detected” it says “Android:HiddenApp-D [Trj]” I try to get rid of it and I cannot, it says that it’s still in use. So I’m trying to look on the internet to find a solution but I’m seeing absolutely nothing. I also am looking through her App’s and see nothing out of the ordinary. I cannot seem to find how to get her “hidden apps” so this is causing me some slight irritation, if anyone knows or could look into these situations please let me know.