I think his mother, but of course she died when Elvis was relatively young. As far as I know Elvis considered family to be important. His father never really went away from his side, though there may have been the occasional argument now and then.
Other people had known him for a longer time, such as JD Sumner and some other members from his family. I think that Charlie Hodge was a loyal friend as well.
Unless I'm very much mistaken, of course.. correct me if I'm wrong!