eMule is listed in avast! On-Access Scaner under P2P shiled. But, you have to use avast! 4.5 version, not 4.1 (see attachment)
avast! 4.5 is still in beta phase, it will be released on Saturday (the 13th of this month).
For downloading beta version (only if you can't wait untill Saturday) search these forums to find out on how to do it...
Cheers !