What's the best Malware software for Mac?

MalwareBytes is often recommended by participants in these communities.

The best approaches for preventing malware are discussed in this article: Effective defenses against malware and ot… - Apple Community

If you suspect you have installed adware/malware. Try running this trusted utility https://www.malwarebytes.com/mac/

Download and run the free version of Malwarebytes.

It was developed by a long time contributor to these forums and a highly respected member of the computer security community.