Little is known about "Mother Death". If she even exists, it is believed she created the two Cosmic Forces that eventually became Veza and Umumtu. She was first mentioned by Yrdon, as he died.
Though some of us are more Mortal than others, the gift of Mother Death is that all things must end. Even you, my friend. I have come to know two amazing Goddesses in my long life, and I am excited to meet their mother, the most powerful Force of all.
It is unknown how Yrdon knew of Mother Death while Veza and Umumtu did not. It could also be that he simply was saying comforting words to his friend.
Please see GM Notes.