Right of Father and grand parents

My son is suffering from his wife mental pressure since 1 year, My son was working in Bangalore and married to Bangalore girl 2017 as there parents was staying near and there was involvement for each and everything by in laws,because of this he moved to Kochi for Job when my daughter in law was pregnant, the difference of opinion& money matter started after this, as she was completely contributing earning to her parents, After my grandson birth they are not permitting us to see him. So we stopped going to there house from 1 year to see our grand son.In public they act very decent but they are very cruel between four walls when they are unobserved by outsiders. Now his wife dont want to go to Kochi ,she gives reason like she dont want to leave job and she want to be with us as we are staying in Mysore(because to show society she is with husband) ,but she is very rude and she dont allow us to be with grandson, this is kind of mental torcher & they threatening to file complaint on us.