Some of us need a nudge into motherhood. In the horror-fable “Bird Box,” Sandra Bullock’s Malorie requires an apocalypse. A reluctant mother-to-be, Malorie finds herself in the middle of Armageddon, facing the unknown in more ways than one.Director Susanne Bier and screenwriter Eric Heisserer, adapting the Josh Malerman novel, imagines a world decimated by a mysterious force that if looked at causes you to commit suicide.