Survivalists' concerns and preparations have changed over the years. During the 1970s, fears were economic collapse, hyperinflation, and famine. Preparations included food storage and survival retreats in the country which could be farmed. Some survivalists stockpiled precious metals and barterable goods (such as common-caliber ammunition) because they assumed that paper currency would become worthless. During the early 1980s, nuclear war became a common fear, and some survivalists constructed fallout shelters.
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!