Divorce papers index number on it. My dad got served. Is it okay to go to court or it will expire papers?

I am not clear on your reference to index number. Do you mean the case number assigned by the clerk's office at the time the petition was filed? You indicate your father was served with a divorce petition, and perhaps additional pleadings. Your father needs to retain counsel or be prepared to timely file his response to the pleadings he was served. This is a very short time frame, so time is of the essence.