Why did Nelly agree to accompany vathy at wutherong hoghts?

Nelly agreed to accompany Cathy to Wuthering Heights primarily out of a sense of duty and loyalty to her as a friend and caretaker. She recognized Cathy's deep emotional connection to Heathcliff and understood the importance of this visit for Cathy's well-being. Additionally, Nelly often acted as a mediator in the tumultuous relationships between the characters, and accompanying Cathy provided her an opportunity to navigate these complexities.