This is clearly domestic violence. You can’t just unsee this. Try to protect your parents first. You need to talk to your wife. This is clearly a disrespect to your parents. No child or their spouse has the right to beat their parents. First, try to talk it out with your wife and find out the reason behind beating your parents. There can’t be any valid reason for doing it. So, you can either make her stop or take action against this.
Firstly, if you don’t want to go to court then you can hire a nurse or caretaker for your parents. So, there will be always someone to look over your parents.
If she doesn’t stop even after this, then you both can shift to a new house near your parent’s house. In this case, you will know what’s happening with your parents but your wife won’t beat them.
If any of the things mentioned above doesn’t work, then you can take legal action.
You can file a case against your wife under Section 506 of IPC, 1860:Punishment for Criminal Intimidation
The husband can file a case against his wife, claiming that she threatens him to hurt himself or his family or property.
Yet again, the evidence is the only thing that can uphold his case.
So, before taking legal action you need to collect enough evidence against your wife.