It's no secret that the death of Kanye's mother Donda West in 2007 has had a tremendous effect on his life. He made this clear during the show, during which he shared an emotional story about when he found out she passed away. Explaining that he had just gotten off a plane, Kanye recalls, "They told me that my mother was no longer here and I could never speak to her again." This led him into "Coldest Winter" off of 808s & Heartbreaks.
Later on, Kanye would attempt to perform "Hey Mama." However, before he could get a word off, he fell to his knees, mic in hand. It was a powerful moment, one that felt personal for Kanye for obvious reasons, but also for the crowd. Understanding the circumstances, they willed him back to his feet by cheering and singing the words he couldn't. While "Hey Mama" was ultimately never performed, what occurred onstage meant a lot more.
You can watch a short clip of "Hey Mama" here.