Resignation on health ground

I was working in a private IT org in bangalore. i had previous history of two times cancer and the employer knows about that. also i had third time cancer attack during employment and underwent a major surgery and was bed ridden for 6 months. employer supported me that time, but i was also supporting the company / managing team via webex and chat on all projects.

till then it was going fine. few months back i resigned from my job from my chennai office as they were asking to come and join in bangalore . stating physical condition, i resigned. 

from that time, about two months salary was also pending. now they not giving full and final and asking me to come to bangalore to sign off. but the issue, i cant travel as i am prone to infection and also i am taking semi solid food only one time, as my half of my mouth is blocked due to surgery. they are not even sharing my pf number. how to withdraw it is million dollar question !

i am telling them to send all the documents to my home address , if any, for signature or send someone, but they are adamant that i only have to come.

i have sent my recent face snap, prevouse mri reports, etc., even then they are not agreeing or completing this formality and paying me.

is it legal for an employer to push an employee like this ? or i should still give notice or go there for full & final ? considering my health condition.