I do not see any of the usual files associated with the Search Marquis Malware in your screen shots. After removing Norton using the above link, check for Extensions installed at Safari > Settings > Extensions.
If nothing is found in there, then I recommend running EtreCheck and post the report using the Additional Text option when posting. John Galt is the master on the Search Marquis malware and you may have come across his article, but I will post it here as well.
Using EtreCheck
Removing "Search Marquis" / "Search Baron… - Apple Community