Unwanted graphic images on Safari

Phony "tech support" / "ransomware" popups and web pages - Apple Community describes these scams and what do to about them.

I ran a couple of scans…no malware or viruses discovered.

Whatever you are using to run those scans, uninstall it. There are no viruses that affect macOS. Phony web pages, phony emails, phony phone calls, text messages etc are just that. Phony. Not malware. Ignore them. If you installed something, uninstall it in accordance with its instructions. Those things are the real threat. They convey no benefit.

Chances are the website your wife is visiting was altered nefariously to provide the unwanted images. Clearing the cache on Safari and not visiting the site should keep the unwanted images from reappearing.