Question

in a fiefdom, a peasant was expected to work the land and
care for the lords children.
take the lords oath of loyalty.
oversee the lords vassals.
maintain the lords estate.

Explanation:

In a feudal fiefdom, peasants worked the land and were expected to swear loyalty to the lord. Caring for lord's children, overseeing vassals, and maintaining the estate were not typical peasant - duties.

Answer:

take the lord's oath of loyalty.