Father is not giving money to my mother for living

My father has bot been giving money to my mother for living for many years now.. I am bearing the expenses wholly from the time I got a job.. but now I want to get the solution to it.. My father is supposed to give money to my mother at least.. He is a govt employee and well earned person.. he is going to retire in January 2020.. he has not earlier given enough money in his entire job life saying to us that he is saving money for future and now also at the time of the retirement he is reluctant to give money to my mother now and not in future too.. when my mother asks for money she gets humiliated by him.. I want to know if I file a case against him, how much time it will take to get the justice so that my mother can get all the money she is supposed to get.. Also I want to know specifically minimum how much money my father has to give to my mother if he earns XYZ according to the law where as my mom is homemaker..