He didn't know SelinaSelina was there at all and didn't come for her, but for DaggetDagget (and ultimately BaneBane). So it was indeed a coincidence that he arrived just in time.
As to the question of why he was visiting Dagget'sDagget's house then, this is explained in an earlier scene. When BruceBruce (or rather AlfredAlfred) does some investigations about BaneBane, he learns that he previously worked as a mercenary for one of Dagget'sDagget's rather dubious projects abroad and that DaggetDagget most probably brought him into GothamGotham.
Bruce: Did you check that name, Bane?
Alfred: He's a mercenary. No other known no names. Him and his men were behind a coup in West Africa that secured mining operations for our friend John Daggett.
Bruce: And Daggett has brought him here?
Alfred: So it seems.
So he concludes that BaneBane is likely doing some work for him and when he lost track of BaneBane and his men after the stock exchange robbery, DaggetDagget was the first point to look for them and get some answers.