Should I rejoin the company after 18 months even if they have not paid my gratuity and other benefits to me after serving more then 5 years in the same company?

I want to now about the process and rules of gratuity being paid by an employer.
In my case, I have been served my 6.7 years in a compny and resign for my maternity just before 20 days of due date of my delivery. My employer didn't give me my increament of 4 month plus my maternity benefits which should be start before 3 months of my due date or as per rules of the maternity act. They never been paid gratuity amount for serving 6.7 years in the company.
At present after 19 months they are calling me to rejoin the company on a new post.

What should I do?

Should I ask for the increamented amount of my last salary which was not paid, along with maternity benefits ( during that period being pregnant, I was serving in the company), and gratuity amount which is due on them after leaving the office 18 months ago.
Or should I rejoin the office on new post without that such things or say the gratitude towards my sincerity to being there for 6.7 years with loyalty.

In my opinion the company which does not care for even the statutory rights of employees is not at all a good place to work. But if you feel that you will not get another opportunity and this is comfortable you can join with a few conditions. First, you should get a confirmation of how the period of absence of 18 months will be treated. If you had resigned at your will, you will have to forget about it but if your resignation just before proceeding to leave on account of maternity was following any direction from the employer, you should ask for maternity benefit in the form of 26 weeks salary. You should reach a consensus as to how to treat the period of absence post 26 weeks. It can be a leave with out pay, no issue but in records, there should be an approval of leave. Finally, you should get a confirmation about your past service, ie, service of 6.7 years. Once the period of absence is regularised it will automatically be linked to the present service. But an agreement is required failing which in future, the employer can deny you gratuity once you leave the company due to any reason. The increment not given to you for the 4 months of service quitting can be ignored but you can demand a higher salary considering the increments for two years when you rejoin now.