Mathilda seems to manage some kind of herbal bussiness in the bog of the Vile Verdant. She offers transport and access to alchemical plants across the treacherous grounds and the opportunity to harvest these plants, all for a nice fee of course.

The party was sent there by the Lord of Embers , after Mathilda had been late on her tribute for a couple of weeks. Apparently she was having some trouble with Bloodsuckles.
 
She offered some supplies and a place of rest to the party, and they helped by clearing out the infestation.