Who is The Wendol's Mother from Eaters of the Dead: The Manuscript of Ibn Fadlan and what is their importance?

The Wendol's mother lives beneath the cliffs in the thunder caves. She is described as a most hideous creature, who looks like the other wendol, but who surrounds herself with snakes as well. Many of these snakes seem to grow from her head.

The only chance Buliwyf and his men have at overcoming the mist monsters is to destroy their mother. They derive a mysterious power from her, and once she is disposed of, the warriors will be better able to rid Rothgar's kingdom of the rest of the monsters.