Botnet Malware

Received a letter (not email) from our ISP (Spectrum) notifying me that one or more devices is infected with advanced botnet malware based on detected activity from my modem. We have tried to download the security suite from our ISP but the AnitBot Scanner is not compatible with Macs. I am unable to clear the history on Safari as some have suggested and the Mac afflicted has two unidentified Extensions which appear and are acting suspicious: PublicFraction 1.0 and BinaryDeveloper with other pop-up windows titled "search.range" asking for permissions.

Can anyone offer some assistance on this matter.

Thanks in advance.