B. Drive south on Park Road until you reach Euclid Avenue. Addresses and street names are always capitalized However, north, south, east, or west, they are only capitalized when they are part of a proper name or are indicating specific regions. They are not capitalized when indicating direction, like go south, or the north of France.
Given that 'blunt' means 'not smart' and that 'mettle' means 'wit; intelligence', I believe that the statement that best paraphrases "What a blunt fellow is this grown to be! He was quick mettle when he went to school" is "This man, who was smart in school, has grown up to be unintelligent".