Zombie apocalypse: Used by some preppers as a tongue-in-cheek metaphor for any natural or man-made disaster and "a clever way of drawing people’s attention to disaster preparedness". The premise of the Zombie Squad is that "if you are prepared for a scenario where the walking corpses of your family and neighbors are trying to eat you alive, you will be prepared for almost anything." Though "there are some... who are seriously preparing for a zombie attack".
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!