What is the appropriate version of Malwarebytes anti-Malware for Mac running
OSX v10.5.8? Your immediate response would be greatly appreciated.
For Malwarebytes AntiMalware to be efficient, it needs to run on a version of Mac OSX newer than 10.5.8. The latest version available on the developer's website is listed to be compatible with Mac OSX 10.9 or higher. There is also no way to download an older version and even if it was, it won't provide full protection.
The first version available for installation is 220.127.116.11 and was released back in 2015, but I doubt it will run on 10.5.8. That is an unsupported operating system.