AdBlock Now is a Chrome extension that triggers our Potentially Unwanted Program (PUP) detection rules. PUPs are programs that may include advertising, toolbars, and pop-ups that are unrelated to the software you downloaded. If users wish to keep this PUP and exclude it from being detected in future scans, they can add the program to the exclusions list. Malwarebytes for Windows can detect and remove the PUP. If you want to keep the extension, add an exclusion of the type Allow an application to connect to the internet.”]
Source: https://forums.malwarebytes.com/topic/276976-removal-instructions-for-adblock-now/