Can my final grade be right?

I would suggest talking to another teacher or your principal/headmaster about this. It may be correct, however, taking points off due to lateness caused by unavoidable cirstances is not permitted in most schools, and the fact that he said you could make it up later and then marked you down for that should get him in a lot of trouble with whoever is in charge. Basically, just talk to another teacher, or get your parents to ring the school and sort it out, the worst that can happen is it will stay the same.