That was Summer and Shaddydog

Summer (light Grey almost White)
http://images1.wikia.nocookie.net/__cb20130318145913/gameofthrones/images/8/87/SummerS3.jpg

Shaddydog (very very dark brown/black, he is the one on the left)
http://images4.wikia.nocookie.net/__cb20120604073444/gameofthrones/images/thumb/8/8e/Bran%2C_Hodor%2C_Summer_and_Shaggydog.jpg/640px-Bran%2C_Hodor%2C_Summer_and_Shaggydog.jpg

Ghost (pure white)
http://images3.wikia.nocookie.net/cb20110625085821/gameofthrones/images/a/ab/Ghost.png
http://images3.wikia.nocookie.net/cb20110302121354/gameofthrones/images/thumb/4/4d/Ghost.jpg/300px-Ghost.jpg