Zara was anxious and worried about her mother and how her mood would be to see her arrive home late at night with the boy she didn't want even within fifty feet radius of her beloved daughter.
The lights in Zara's home were off. Well, it could mean that her mother had not returned from her work or that she had waited and waited for her daughter anxiously before returning to bed. She was terrified of getting scolded by her mother.
Zara chewed her fingernails, she was very afraid to enter her house. Add to the fact that Ryan was the one dropping her home. If her mother was home and she saw Ryan with Zara, it would blow up to a whole new level with her mother already pissed about her daughter being late.