My wife Father File a suit Return Back to my Wife property

Respected all, This is Nagesh. My wife name is Anjali Devi. We both have in love since 2010 and married 2015 April 6th in a temple. After Take my wife with me to my house. My family consider my Love and Marriage. But my wife family not agreed our marriage due to Caste and Economically we both are different. The next 3 days we are suffering so many problems with my wife family members. 1 week later we legally registered our marriage in INDIAN MARRIAGE REGISTRATION ACT. Coming to Case : My wife father give a worth 5,00,000/- property (House Half Portion) in 2015 January. for my wife marriage purpose. When my wife marry me he is not adjusted. Create some issues in front of higher people in our town. then my wife family went to Local PS for complaint on my wife. The police man said to my wife family they are majors and they married legally so we don't have right to file a case on them. After 6 months my wife father file a suit through layer on my wife for asking back the property Court notice to us in March 2016. in that file they mentioned our marriage is illegal and we both are not same caste and we both living illegally. So that case my They asking my wife property back. We consider a Local Layer and he will replies court notice. So Please requested my self what we have to do. Please tell us the proceedings for our case. Thanks & Regards