Can you be terminated while on company disabilty? Also doesn't the company suppose to offer cobra at time of termination ?

Yes, being out on disabilty does not protect your job.  If you are not able to work, the employer can lawfully terminate you unless you are FMLA covered (and even then you only get 12 weeks of FMLA leave) or potentially if leave from work is covered as a reasonable accommodation under the ADA. The employer (assuming it has 20 or more full time employees) is not required to offer COBRA at the time of termination.  The employer must provide notice to the health insurer within 30 days of an employee termination (including resignation) and the insurer must notify the employee of the COBRA options within 15 days.