Arvena Thelas' House is located west of Anvil's north gate. Arvena Thelas is the resident of the house. The top level is split into two and accessible by stairs. There is also a large basement which is home to Arvena's rats.
The Guild has been asked by one of the locals, Arvena Thelas, to take care of a rat problem in her basement. The Guild believes it is to clear out the rats, but the Guild member sent isn't fighting rats - they're defending them.