Senior Citizen being harassed by cousins

My mother lives in our ancestral house which was made by my grandfather. During his death he made a will and gave gf rights to my mother and 1st floor rights to my cousin. My mother lives in the ground floor while my cousin brother and his wife lives in 1st floor. My mother is a senior citizen with >60 years of age and widow. She lives with my younger brother and his wife. My cousin and his wife constantly harasses my mother and create nuisances. They block pipes of their bathrooms to create seepages...they come and fight regularly..they threaten to implicit false case against my brother. They keep finding new ways to trouble her - throwing salt & garbage in her garden, destroying her tulsi plants, locking her door from outside, removing main door locks, creating seepage issues, blocking water from overhead tanks, etc etc so that they can have their way. She is a lot of mental stress which is impacting her heath. Want to know what action can she take to stop this mental harassment and troubles? Can my cousin be implicated in a criminal case for troubling a senior citizen? What rights she has to fight this nuisance?