What are: AdjustableProduct, AssistiveFile, and InitialWindow?

I'm running High Sierra 10.13.6 on a iMac (late 2009) with Safari 13.1.2. Three applications keep on showing up in Safari Extensions: AdjustableProduct, AssistiveFile, and InitialWindow. To uninstall them, I am directed to deleting the files which are in the Applications folder. When I delete them, they come back. On occasion, they appear to launch, on their own, and apparently launch Safari in the process. The extension usually or always quits itself, sometimes Safari quits on its own and sometimes it stays running. I have deleted them several times now, and they keep coming back.

I have done a few searches for these extension and have been unable to find any information about them. I suspect malware but really don't know anything about anything. If the extensions/apps return, what should I do to get rid of them?