How many VHF system can be in MEL for an A340?
There are three VHF systems on A340 aircraft, as described here:


  Item: VHF Systems
  Number Installed: 3
  Number Required for Dispatch: -
  Remarks or Exceptions: Any in excess of those required by FAR may be inoperative provided it is not powered by an Essential Bus and not
  required for emergency procedures.


MMEL is required by FAA:


  A minimum equipment list is required in the United States by the
  Federal Aviation Administration:
  
  
  When operating any turbine-powered aircraft such as jets or turboprops.
  When operating under part 135 (Commuter and on-demand operations)
  When operating under part 125 (Non-airline large aircraft operations)
  


MEL for FAR 121 is discussed here.