While your overall performance is good enough for any school, the disparity between the verbal and quant is probably the reason why the school asked for a retake. In other words, the school has told you to improve your verbal. With a score of 49Q, you probably don't need to invest that much time in guidebooks for math. Go for the
GMATClub tests to keep you sharp, though.
For verbal, you need to work overtime. My suggestion is to use
MGMAT SC and Powerscore CR and reinforce those concepts with as many high quality questions as possible (OG,
MGMAT online banks and CAT's, GMATClub forums). For RC, use the OG material as well as the LSAT SuperPrep. That book also has some decent CR practice.
And don't stop reading the SC book. As soon as you finish, start over.