What information did Valli require to plan for her first journey? How did she get it?
Or
Why did Valli take so much interest in the conversations of the passengers?
Or
Why did Valli ask the passengers and neighbours about the bus journey?
To plan for her first journey, she needed to know some details like the fare, the duration of the trip, the route of the bus, etc. She gathered the required information by listening to the conversations of the passengers. Moreover, she asked her neighbours some discrete questions about the bus.