I read that being buried alive was a primal human fear dating all the way back to ancient Egypt back when the Pharaoh's slaves would be trapped inside the tombs along with them after they were mummified.
The poor woman must have been too terrified to even think. Just imagine if she had been able to calm herself from screaming she probably would have retained enough oxygen in the coffin to last a little longer.
At least they didnt cremate her.
