Step 1: Understanding the Question:
The question asks to identify the character who shouted "Stop the bus!" and the reason for this action, based on a specific event from the story "Madam Rides the Bus."
Step 2: Identifying the Character and Context:
The character is the young girl, Valliammai, known as Valli. This event occurs when she is trying to hail the bus to the town for her first secret journey.
Step 3: Detailed Explanation:
The voice was raised by the eight-year-old girl, Valli. She was standing on the roadside, waiting to catch the bus for her first ride to the town. As the bus approached, she raised her tiny hand to signal it to stop. However, the conductor, in a jovial mood, teased her and started to drive the bus away slowly. To ensure she was not left behind, Valli shouted commandingly, "Stop the bus! Stop the bus!" to make her intention clear and assert her right as a passenger.