Judd Hirsch stars as Dr. Sigmund Freud and Tom Cavanagh is C.S. Lewis in the West Coast premiere of “Freud’s Last Session” at the Broad Stage. The atheist psychoanalyst and the philosophical Christian author discuss life’s most important questions—love, sex, death, and God—Jan. 11–Feb. 10, with post-show talkbacks Jan. 13 and 17.