You followed Bonnie's advice and, together with the Marshal, successfully completed the previous quest. To complete this mission in Red Dead Redemption, return to the camp at the woman's house and talk to her. You will have a very candid conversation about personal life. Afterward, the woman will ask you to help herd the cattle to the pasture. Mount your horse and follow her to the barn. Bonnie will be leading the herd, and your task is to keep an eye on the cows from behind.
As soon as the herd of cows reaches the pasture, you will receive +32 dollars and +50 points in the Honor category.