Starting in 1969 on “Laugh-In,” Lily Tomlin has created and played a whole theatre troupe’s worth of characters. But her latest — a ballsy, fiercely protective grandmother in the movie “Grandma” — might be the closest to her real self. Also, we hear from the composer of the theme song for “Seinfeld” about his reaction to the trend of mashing up pop songs with his most famous tune. And the Pulitzer-winning playwright Annie Baker talks about why some people love her work — and others can’t stand it.