But fret not, it is expected to return soon.
A friend of mine told me that Avast Mobile Security is not available at the Play Store, and that he found a thread at the Avast Forums, about the same.
A reply to the thread, from a company employee confirmed that Avast Mobile Security has indeed been pulled from the Play Store to fix issues.
Mobile team members were notified on Saturday that there were some issues with AMS and Avast Cleanup that needed to be addressed, and it took a little while for them to coordinate since it was the weekend and some folks are on vacation. At this time, we don’t have any other details except that they assured us that they are working now and hope to have it restored very soon.