What if a Daughter in Law is harassing all in the in-laws family?

Hello all esteemed lawyers, I am looking forward to your kind advice for a family who is very near and dear to me and I have known them for years. The family today constitutes of 77 yr old father, around 70 yr old mother, 38 yr old son, 34 yr old daughter-in-law and 37 yr old (unmarried) daughter as well as a 5.5 yr old grandson (son to the son and daughter-in-law). This family is very religious and very noble and humble family. The son married this girl in 2009, it was a love marriage but permitted by both families. Since the marriage, The daughter in law is ill treating the son (her husband). She provokes and instigates him to a level that he also at times looses his cool and it turns out into a fight. The couple used to stay alone until they were blessed with a baby boy (who is now 5.5) after which the son's parents and sister moved in to help and also since the son wanted the family to be together. After some time the lady (daughter in law) started ill treating and abusing (verbally) her parents-in-law and sister-in-law. The sister in law is a well-to-do professional but still tolerates her misbehavior due to her religious and family values. The daughter in law also does not take proper care of their 5.5 yr old son but shows off a lot that she is taking care. Well she is very good at arguing and can prove anyone wrong. Due to all these tensions, the son (in the family) is stressed out and not being able to even pay proper attention to his service. The son has recently purchased a home (flat) where the family is staying together in his name. The family (all members) are really harassed like anything by this lady and the son now many times looses his cool and it gives birth to internal abusing and fights between the couple. The family and son are worried for losing their reputation in society, money (in case alimony is demanded) and their 5.5 yr old son. What could be done in this case? Kindly advice. Thanking you in anticipation.