The episode info says that it will be an unexpected loss to a student (most likely someone in glee club). The unexpected part probably showing that the person isn't old or sick. Also they say that the person that dies is a beloved character to the show (meaning we know this character). Also there are a lot of sources saying it is a female character, but not someone in the glee club or Mr Schuster, Emma or Sue.
So who are the extra female characters: April, Coach Beaste, Jean, Becky, Quinn's mom, Finn's mom, Terri, Sunshine but none of them fit the info as April, Coach Beaste, Jean, Becky, Terri and Sunshine mean nothing special to any particular student in glee club. Sources say that it isn't Finn's mom and Quinn's mom isn't exactly a BELOVED character to the show. So what was I thinking who are the only two people who fit all of the above.............They are both beloved, female, they both have a special meaning to a certain glee club student and neither is old or sick. And they both haven't been seen on the show for a year so imagine how unexpected it would be if it was Ms Corcoran or Beth :O right?? Ms Corcoran is rachel's mom and Beth is Quinn and Puck's daughter.