Company Acquisition: Not satisfied with the new offer.

Hi, My company where I work has been acquired by some other company. I have worked here for around 4 years now. The CEO is saying the company will no longer exist starting next Monday 16th July 2018. We have been informed this just yesterday 11th July 2018. Our company has a very good growth and was always in profit. Now, we are being asked to resign from this company. and They are asking us to sign the new offer letter for the new company in which there is no mention of any merger or acquisition. My appraisal was pending next December. So, Now they have given me a 5% salary hike and saying the next appraisal will be done next April 2019. My question here is I am not satisfied with what I am being offered like the salary and terms. I have been worked for 4 years and if would have completed one more year, I was eligible for the gratuity. So, Can I resign and ask them to pay me for the notice period which was of 2 months? Currently, I feel like I am being forced by the decision they have already taken. I talked with them to increase my salary more, but they are saying now it's not in their hand. Please advice me. Thanks.