Answer: We know for sure that there is an established relationship between Casey and Mabel.
Explanation: "She has met Mabel, a kind elderly blind lady who has asked Casey to spend an hour each day helping her around the house".
Everyone
done his or her homework.
Explanation:
Everyone is singular and, therefore, require singular verb.

She began The Outsiders at the age of fifteen, inspired by her frustration with the social divisions in her high school and the lack of realistic fiction for high .