There are certainly details in the story that suggest that Mrs. Jones was a large woman.

The first paragraph uses the word "large" to describe Mrs. Jones. The first sentence of the story tells us that Mrs. Jones is a "large woman with a large purse that had everything in it but hammer and nails." 

When a young boy tries to steal Mrs. Jones' purse, the text tells us that "the large woman simply turned around and kicked him right square in his blue-jeaned sitter."

During their conversation, Mrs. Jones remarks upon the boy's dirty face and asks whether there is anyone at home to tell him to wash his face. The boy answers “No’m,” which prompts Mrs. Jones to declare that she will wash it for him that evening. The text then tells us that the "large woman [started] up the street, dragging the frightened boy behind her."

At the end of the story, the text tells how the boy looks back "at the large woman in the door" as he leaves her house.