Final answer:
In 'The Mysterious Benedict Society' by Trenton Lee Stewart, Kate Wetherall called the woman Reynie referred to as 'The Pencil Lady' Mrs. Johnson.
Step-by-step explanation:
In the book 'The Mysterious Benedict Society' by Trenton Lee Stewart, Kate Wetherall, one of the main characters, referred to the woman Reynie called 'The Pencil Lady' as Mrs. Johnson. She gave her this name because the woman always carried a pencil with her. Mrs. Johnson played a significant role in the story as part of the mysterious organization that the main characters were investigating.