As heart breaking as this is, you can't criminally prosecute every traffic accident. In every traffic accident, you can find negligence. There has to be gross negligence for manslaughter, not just negligence. In other words, the person has to have blatant disregard for the safety of others. Making a dumb mistake, even if it kills another person, is not criminal.
Civil liability is a different matter. Absolutely the one who opened the door should be sued for wrongful death.