Is expiation and blood money obligatory upon someone who collided with a bus that suddenly overturned in front of him, leading to the death of two of its passengers, knowing that the bus driver was not the original driver and did not have a license?

If driving within the speed limit and the driver was unable to avoid the collision due to the bus suddenly swerving and overturning in front of him, then there is no sin upon him, and he is not required to pay diyah (blood money) or kaffarah (definition) (expiation), because he did not transgress or act negligently. If the accident was due to force majeure or the action of the aggrieved party, then the driver bears no responsibility.