SOLUTION:
Lou had the Coke,
Ted had the Diet Pepsi,
Mary had the 7Up, and
Murray drank the coffee.
LOGIC SEQUENCE:
Clue 1: Murray did not have the 7Up.
Clue 2: Ted had either Pepsi or Coke. Mary had either 7Up or coffee.
Clue 3: Lou drank Coke (the only Coca-Cola product of the four). This means that Mary had the 7Up (the only option left for her), which leaves Murray with the coffee and Ted with the Diet Pepsi.