Harrassement - Relief help

Sir, I am a State Govt. Servant. I am a Sunni Muslim. I have two Step brothers. After the demise of my father having grudge against my family they are harrassing me for the share in my mother's property stating that i am enjoing the benefits of the entire Residential property not giving the share to them. They gave several complaints in my office to take action stating that I have involved in illegal activities.Since two years they are harrassing cruelly and have tornished my family's image in our locality and also in my office by telling all wrong things about me and my mother. My question to respected experts is : 1.Are they right in their attempt. 2. What action can be taken for tarnishing our image. 3. Can we stop them not to proceed further in doing false deeds. If so, under which rule they can be fixed. 4.Can we recover the penalty for harrassing / defaming us. If so, how much amount can be demanded. Plz.help and guide us in living a peaceful life.