The child ran into the road and was killed by a car. Is it the responsibility of the roadside stall?

There should be no responsibility for setting up stalls on the roadside.

Just because a roadside stall sees this scene doesn't mean it has something to do with it. If there are other special circumstances, it will generally be identified by the traffic police. The traffic police will issue an accident certificate, make a responsibility determination and divide the responsibilities of both parties.