My dad got a notice from advocate for cheque bounce..Reg

Problem is between the lady (who gave Rs 15,00,000/-)&to my dad. She is a family friend to us through her cousin of our neighbour and she gave Rs 15,00,000/-(fifteen lakhs)without bank transaction for our urgent expenditure with 5% interest on Oct 2013. For that amount she did't get any written statement but after one year she requested us to give a blank cheques for a security reason, So myself and my dad went to her house on July 2015 for giving cheques & she demand him to give cheque for Rs 30,00,000/- she tried to convinced for long time he disagree with her then suddenly she threatening us like she is going to attend suicide with letter name of ours, we had no other way so we gave seven cheque leaves of (Rs 10lks,5lks,3lks,3lks,3lks,3lks,3lks)respectively he had told her that "don't put in clearance this is only for your security purpose when i get money i'l take back the cheques" she agree with him.Then we gave Rs12,50,000/-(Rs twelve lakhs) through banks in the name of her,her daughters and her husband name. After receiving these cheques and money her behavior and way of talking had changed, In between july 2015 to Nov 2016 she,her elder daughter & her friends came to our house about 3 to 4 times each and every time when they come and shout like anything vulgarly for she demanding of Rs 60,00,000/- we did't accept.After this only we realized that they all are in well planed to get Rs 60,00,000/- . But now she entered date in all cheques and bounced against my dad except in Rs 5lks cheque because he entered date on it and all other cheque are without date mentioned.We got notice on 19 Nov 2016. what should we want to do my parents are illiterate for me also don't have knowledge about these things so please give us some valuable points.. ThankYou