JEFFERIES MAKING MARKET IN USAIR <U> Jefferies and Co said it is making a market in the stock of USAir Group Inc at 48-1/2 to 50. USAir received an offer from Trans world airlines to buy the airline at 52 dlrs cash per share. USAir was halted on the New York Stock EXcahnge for dissemination of the news. It was indicated at 47 to 54.