Malwarebytes is the best in its category.malware is different from virus,e.g.bundled adware with many freeware softwares now-a-days are not virus in the sense that they don't actually infect files or processes but they do impact pc performance.free version can only do manual scanning(no real-time protection) but combined with a free good AV like avast or avira(or even paid ones like kaspersky,norton,eset etc) that is all you need.just scan your system manually once a week or after installing some freeware & that's it.
Malware is a short term for Malicious software that includes virus,worms,bots,trojan/backdoor, etc that can cause harm to your PC.
Adwares,spywares,ransomware are totally a different category.
But the reality is, their differences are blurring due to the capability of malicious programs that can do some/all the above.
Ex: An adware once get installed onto your PC can download an backdoor stealthily so bots in the internet can control & steal your Creditcard/Personal information from your PC.
It's a Suite of tools that help accomplish great things off your PC
Malwarebytes like any Antivirus helps you remove/protect from KNOWN Malwares.