Employer FIR against me what should i do?

Hi sir, Recently i joined a company in March 2019. Company will provide me only offer letter. After 02 months i have asked for my appointment letter payslip & also claimed my tour bill. They only provide me march & april payslip. After 03 months company has given me some cash for my expenditure without any legal paper. after 06 month i have resigned from the company by giving 05 days notice period as there was no clause of any notice period in my offer letter. Now when i claim for the settlement they have refused to provide me my last month salary, since i didnot give any notice period to the company. Employer is a gurgaon,UP based company. They don't have any off in west bengal. I am working as a residential employee. Also they refund me the cash which was given by company. i just mail them by adjusting the money with my dues (40 days salary & tour bill) i will pay the balance to the company but the company didnot agree to pay the salary as i have not given notice period of 30 days. But they agree to pay the tour bill. Company told me that if i did not refund the money they will FIR against me with 420 charges. All the documents/emails are with me . company also provided PF. Now what should i do?