SEASON FINALE: It’s the last episode of the season for Parenthood, and NBC has yet to decide whether to renew the series for a Season 6. That hints at a failure of leadership, or at least nerve, in the NBC executive suites, because Parenthood, by far, is the best show the network has on the air right now. Its renewal should be a matter of pride and certainty, not a tough call. Watch tonight, and while you’re wiping away tears and wondering what will happen next to these characters, ask yourself: How could this outstanding family drama series not be renewed?