Legal notice from a grooms family

Dear Sir, This is on behalf of my friend shilpa who is a hindu keralite and curently working in Oman. She got engaged to a guy named deepak who is also working in Oman on last Jan.2020. They met on facebook and this friendship changed to a marriage proposal. During this time the girl was in india and later she also went to oman for a job. After coming close to him only and with the interaction she had with him she found that her decision was not right since he use to show bad behavior towards her and use to shout on her unnecessarily and would never give her a chance to speak her mind or her choice. There were many fights between them but somehow they got engaged because the girls parents were not ready for this proposal at initial stage and somehow they agreed. So for the family pride she went through the engagement. After engagement she also came to know some more truths about the guy and then she decided to call off the marriage. All the expenses made for the engagement were shouldered by the girls family. Now the boys family have filed a case against the girl and her father and are asking for a defamation of INR 16 lakhs. They are also spreading rumours that the girl has a mental problem therefore she is moving out of this marriage. What can be done at this situation ? The girls family is not so financially strong to bear this 16 lakhs amount. Please advise.