B1/B2 Emergency appointment

Hi connections,

I need some clarification to request Emergency appointment for B1/B2 visa category. I am going to do a heart surgery in another 2 to 3 months. i would like to bring my parents with me during my surgery time. My mom have B1/B2 visa already, i need to request visa for my dad. In this case can i request Emergency visa appointment for my dad?

Note : i have completed the DS160 form and trying to book the appointment for last 3 weeks. But i didnt get the dates to book the appointment.

Please consider this as urgent case and let me know your suggestion on this.