People making false allegations can I file defamation case

My mother has room project in naigaon. Some people booked the room there and now want to cancel the same. My mother told them after selling their room she will return the money. But this people want money back on urgent basis which is not possible for her. I am advocate and nowhere involved in this matter. This people sending me notices that I have cheated them. They are thinking if they will trouble me my mother will give them money. Can I file defamation suit against these people.