vote_for_palpatine said:

ESB: Vader wants Luke Skywalker desparately. He is using a ton of Imperial resources to track down this one guy. (Of course, we do not yet know about their blood ties) True, finding Skywalker means finding the Rebels, but the course of the movie makes clear that finding the Rebel base is the second bird - Vader's one stone is aimed at Luke. (If that weren't the case, why did not Vader's ship try to follow the Rebel fleet out of Hoth instead of the Millennium Falcon?)

I figured that Vader thought Luke would be on the Falcon with his dear friends. He knows that Luke would risk his life to try and save them, so it stands to reason maybe the gang would stick together during an evacuation.