The first wish was for 200 pounds (money). That was fulfilled by the Whites' son getting killed at his workplace. The next two wishes come out of that wish and result.
The second wish was demanded by Mrs. White. She was so sad about her son's death that she made her husband wish that he would come alive again.
Some time later (about the amount of time needed to walk from the cemetery to the Whites' house) there was a pounding on the door. We don't know what it was, but it's implied that it was the son's body risen from the dead as some kind of zombie.
We aren't told what the third wish is explicitly, but it is clearly a wish for the son to be dead again because after Mr. White wishes it, there is no one out on the street.
Of course this is a perplexing story exactly becuase we can never know if ANY of the three wishes are fulfilled.
The first wish is for two hundred pounds. The day after the wish is made while holding the monkey's paw, the White's only son, Howard, is caught in some machinery at work and gets mangled to death. The company says they are not responsible for the horrible accident, but they give the Whites 200 pounds as compensation for their loss. Of course they associate the 200 pounds with the supposed power of the shriveled, old monkey's paw, but who's to say for sure that the paw had anything to do with the money? It's a problem of confusing cause and effect, something we all do all the time.
When Mrs. White gets her husband to wish for their son to be alive again, it takes a while, but there is eventually a knocking at the door. Is it mangled Howard come from the grave knock, knock, knocking at the door? Maybe, maybe not. Believers in supernatural powers think yes, others think no. Maybe it's just the wind, or some lost stranger, or a late night FedEx express delivery that needs a signature. Mr. White is so horrified by what might be on the other side of the door, that he finds the paw and, just as the Mrs White is about to open the door, he wishes Howard dead again. The knocking stops. Well, if it was poor Howard knocking, then he must have gone back to being dead again. Or the knocking was caused by something or someone else entirely and just stopped as capriciously as it had started. Or maybe the FedEx guy gave up and figured he'd try again first thing in the morning.
In short, there's no way of knowing if any of the wishes were fulfilled and no one will ever know. But aren't you glad you asked?