My son very fierce to my helper. He can throw things to her when she try to stop him. He is p2 now. His grandma most of the time around but occasionally he will be taking care by my helper. What should I work?

That's not very nice is it? Hmm you should tell your son that he cannot treat people that way. Tell him that your helper is someone's mother, some's sister, someone's friend and most importantly a human being like him. Ask him how he would feel if someone treated you or his grandma that way? And how it would feel if someone treated him the same way... Respect begets respect and I think that's an important lesson for everyone -- both adult and children.