Where would you find a short easy to understand definition of the word vanguish

Read the following excerpt from the way to rainy mountain by n. scott momaday: the young plains culture of the kiowas withered and died like grass that is burned in the prairie wind. there came a day like destiny; in every direction, as far as the eye could see, carrion (animal carcasses) lay out in the land. the buffalo was the animal representation of the sun, the essential and sacrificial victim of the sun dance. when the wild herds were destroyed, so too was the will of the kiowa people. which phrase in the passage most strongly contributes to its overall tone? a. day like destiny b. lay out in the land c. far as the eye could see d. withered and died like grass