User blog comment:FairyRaven/Fairy Tail Chapter 389: The Twin Dragons vs. The King of Hades, Review and Commentary/@comment-6152051-20140620094151/@comment-7418318-20140620095524

I agree. They probably came to ask the details about Erza's hasty message, which probably means that it was only the two (or four) of them who came and when Magnolia was in ruins, they just followed the trail of destruction and explosions and ended up in Plutogrim's remains.