Termination without mentioning any reason

Dear All, I have been working in a company since 5+ years. last month 10th Nov i got call from reporting officer in that call he said company situation is not good and i have to resign with immediate effect without any benefit then only i will get my previous Oct 2018 month salary. I refused the same and i asked that release my salary then i will put my resignation. he asked me to send mail to management. I did that. After sending 5-6 follow-ups mail there is not revert from company side. suddenly on 5th Dec HR sent me termination without mentioning reason and mentioned back date of 25/10/2018. In that termination mail they mentioned that i have been informed verbally. I called HR and she replied company situation is not good and i have to resign. they will issue me releaving letter and will pay my dues in FNF. people who put resignation in August 2018 yet to receive their FNF. they will not give me gratuity also. I have been working as on date normally. I am getting reply of mails from reporting officer and other team member related to work. But no revert on salary mails. I am putting my attendance as on date.working normally. Pl. let me know what are option for me.