I'm not quite crazy enough to say that epinephrine will help you survive the inevitable zombie apocalypse (you can go here for that). I'm just suggesting in a roundabout way that if you happened to be in a situation where something was trying to eat you, the increased heart rate and blood flow to your muscles brought on by a well-timed dose might just save your life.
To me, the best option is to store emergency food. How much? If you have none, store enough for a few days. If you have enough for a few days, get enough for a week. How much you store depends on what time frame you think you're at risk for having to be completely independent. The early settlers of the southwest liked to store enough food for a whole year and still do to this day!