Daughter in law left home with grand daughter after a verbal quarrel

My daughter in law had always misbehaved with us. On 2.2.2018 at 11.30 PM she thrashed her daughter of 21 month. We including my objected to this. There was no physical altercation . We only said that she should not have done like this to such a little child. It was late we all slept. My son slept in a separate room that night. In the morning I saw her in the home till 9.00 AM. But near about 10.00AM she left the home with the child without informing any one probably to her parents home. There is no communication from either side till yet. What should we do. We are Hindu.