The Alfred Hitchcock Hour: "Final Escape" (1964)

A spoilt rich woman goes to prison and obviously wants to get out.

She hatches an escape plan, bribing the prison mortician, whose responsibilities include carting out the corpses of dead prisoners.

The plan is that she will climb into the coffin with the next dead prisoner and be buried alive, later the mortician will come and dig her out from the graveyard.

The plan goes well, but while laying waiting, buried in the coffin, she starts to wonder why the mortician is taking so long. She strikes a match inside the coffin and what she sees horrifies her!!