Dowry harassments

My sister was engaged on may 28th 2023, The boy said he doesn't want any gold he wanted everything in cash only before engagement we had spoken to boy's mother and the boy as the boys dad is no more about paying the money only through bank transfer for which mother & Son had agreed, We had a Invitation pooja on 28th November as the marriage date was fixed on 26th Feb 2024.We requested the boy to give his bank details for the transfer of money Rs.400000/-(earlier they had demanded Rs.500000/-) later they agreed to Rs.400000/-. Now the boy and his mother are telling they will not take the money through bank transfer they want cash, earlier they said they don't have any objection in my sister going to job after marriage but now they are saying she has to resign and be at house, as they have 3 floor house so they want her to take care of the house. Hardly 15 days are left for marriage now the boy and mother are threatening if we don't pay cash and ask my sister to resign they not allow the marriage to take place nor the boy will tie the knot to my sister The boy says he has joined insurance company so he cant accept the any amount in the his salary account as he his binding of "AML guidelines" but when we check the CA also said he can open a separate expense account and take it as my sister had taken loan to fund her marriage and entire Rs.400000/- is transferred by Yes bank as loan amount to my sister account. Kindly advise what should we do now what action should we take. Regards Gajendra .