In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.

Passage: After the death of her mother, Carrie McLaughlin has been living with her grandmother in Pittsburgh, Pennsylvania. When her grandmother needs to go to a nursing home, Carrie has to move in with her father Hank, a rancher in Wyoming, whom she hasn't seen since she was a baby.
Initially reluctant to adapt to country living, Carrie soon meets Flicka, a beautiful black Mustang that previously had belonged to Carrie's cousin Katy, who asked Hank to look after Flicka when her father sold their own ranch. Flicka is wild and dangerous and, according to the ranchers, longs for Katy. However, when Carrie is attacked by a rattlesnake, Flicka saves her and the two form a bond. Carrie also meets Jake, an attractive ranch hand hoping to become a country singer, and Amy Walker, the proud and arrogant daughter of a neighbour. Although Jake and Carrie take an immediate liking to each other, there is instant animosity between Carrie and Amy, mainly because Amy also likes Jake.
When Carrie disobeys her father's rules regarding visits to the nearest town, Hank decides to punish Carrie by temporarily relocating Flicka to the farm of one of his ranch hands, Toby. After a midnight visit by Carrie, Flicka tries to follow Carrie home to Hank's ranch, but accidentally ends up on the ranch belonging to Amy's father HD Walker. Upon entering the Walker ranch, Flicka damages a fence and releases some of HD's prize cows. At Amy's request, HD asks for Flicka as payment for the damage, threatening to turn it into a lawsuit if Hank refuses. Amy then starts training with Flicka for a championship, but performs poorly during the actual competition because of Flicka's fear of the crowd and camera flashes from the audience. HD and Amy decide to have Flicka slaughtered the next day, but Carrie frees the horse during the night and sets her free to join a nearby herd of Mustangs.
What is the last name of the person whose grandmother needs to go to a nursing home?