It means: it would be kind of you if you could come pick us up (or give us a lift). The "seeking" meaning comes from the fact that, when you go "chercher" a friend to bring him to your place (for instance), you don't just pick him up randomly, you go to this person (you "seek" for him) and drive him back home.
Now I understand the meaning of the sentence. Person_A together with his family came back from a short trip after visiting Person_B. Person_B picked up Person_A at the train station. I think the typical translation will be;