1. Mother can lodge Police FIR against your nefarious Wife, for offences like threatening, intimidation, breach of trust etc....
2. Wife would be arrested & released on filing bail bond and criminal case would proceed in local magistrates court.
3. After above, anticipatively Wife would file a domestic violence & dowry case against you and mother, leading to jail time & bail & whatnots, thus compounding life for everybody.
4. Try hiring a enuch, as Security Guard for Mother .... apprehensively this would solve most problems.
Keep Smiling .... Hemant Agarwal