According to the prologue, the thing that will end the feud is…

the royal decree of the prince to end the fighting.

the deaths of every member of both families.

the marriage between these families’ children.

the deaths of these families’ children, who fell in love.

the last one

Explanation:

she is later raised by him and his wife, madame valmonde, who sees her as gift from god, as the couple cannot have their own children. later, desiree falls in love with a wealthy man, armand aubigny, and they get married.

b is the answer.   i sat on the lumpy sofa, totally exhausted, with a bad taste in my mouth, wondering what i should do next.