I think "hit" is better. When people say someone is crashed, they usually mean that person is overwhelmed or extremely sad.

The boy cannot be "crashed" by a bus. That's not a correct usage. "Crash" is an intransitive verb. You can say "the bus crashed." You can't say "the bus crashed the boy." There is a completely different word, "crushed," which means "damaged by pressure, or being under a heavy weight." You could say that someone was "crushed" by something. You could say "the bus didn't hit him, but the wheel of the bus ran over his foot and crushed it."

If you wanted to use " crashed " you could say The little boy came near to being crashed into by a bus.

I would say "The little boy was nearly run over by a bus." or "The little boy was nearly knocked down by a bus."