"Drummer" was once a well-known term for traveling salesman. This unnamed drummer is imagined by Jefferson observers to have oversold some commodity to Wallstreet Panic Snopes, thus making it necessary for him to borrow money.
Miss Wyott is a teacher in Jefferson, but the narrative notes that her "own people" - that is, her ancestors - "had come from the country (her own branch of it remained there where they had owned the nearest ford, crossing, ferry before Jefferson even became Jefferson)" (154). (In The Reivers Faulkner re-names the family that owns this spot Wylie.)
Although she is never named, Mrs. Wallstreet Panic is memorably characterized. When she first appears at school in Jefferson, the teacher, Miss Vaiden Wyott, instructs Wall that "this is she. Marry her." He does. His wife is described as a "tense fierce not quite plain-faced girl . . . and a will if anything even more furious" than Gavin's in opposing the rest of the Snopeses (154).
Flem Snopes watches "clients coming and going to leave their money or draw it out" (146). Many of these customers are alarmed when they find out Flem "had withdrawn his own money from the bank of which he himself was vice president and put it somewhere else" (274). Some of the bank's patrons inform Wallstreet Panic's wife that despite her orders he has asked Flem Snopes for a loan to save his business. And presumably one of these people is the "somebody" who, according to Charles, "claimed to have seen Mr Snopes himself, unchanged too, unhurried and unalarmed, . . .