Technically, either could. What you really need to ask is "what will need more work?" or "what will need more force to stop it in the same distance?"
The bus is heavier. As such, it has more kinetic energy than the car at the same speed. To get rid of this energy, work must be done on it. The bus has more energy, so more work is needed.
Work is force multiplied by distance. What all this means is that if you keep th distance the same, the bus needs more force to stop it. But you could keep the force the same and they'd both still stop- but the bus would move further before it stopped.
