Filing resignation letter and getting EoSB without being in the UAE

Good evening, madam!

I worked in Dubai for 12 years at a hotel. I left for a short vacation. My mother became very sick and there is no one here to take care of her.

I decided not to come back to Dubai. I have sent my resignation letter to HR but they said that I need to send my passport. I can't send my passport by courier or with friends; it's illegal.

How can I get my gratuity?

How can I cancel my visa so, in the future, I can come and work again?

Kindly let me know!