The “While” indicates that the second part of the sentence will contrast with pushing forward— due to the approaching winter, the colonists need to stay put and conserve what they have. Only “steward” and “husband” mean this. “Sell” and “peddle” don’t work because there’s nothing in the sentence to indicate that they need to sell or buy anything. (And why would you sell your resources when a hard winter is coming?) “Procure,” which means get or acquire, doesn’t work because the sentence references their “existing resources.” “Upend” also doesn’t work because of its meaning; the colonists do not need to stand their resources on end!