Hi, betseyd112. Welcome. Are you signed in as an Administrator ? Normally if you right click on a file and you have NIS or Norton 360, it will show in the list along with MalwareBytes.
In my case it's NIS and in the option list it's listed as Norton Internet Security, and when you click on the small arrow, the option to Scan Now is shown.
What product are you using ?
Are you using NIS or Norton 360, and is it fully up to date ?
The current version of those is 21.3.0.12, which you can check by going to the main UI and selecting Support/About.
If you've downloaded the stand alone Norton Security Scan, you may not have those options.
Here is some info on it. I don't think you can scan individual files.
https://support.norton.com/sp/en/us/home/current/solutions/kb20080415160906EN_EndUserProfile_en_us