Sorry for the late reply! To get Ending C, you need to unlock the combination lock on the sanatorium north lobby's front door.
Thanks, i'll try that(if i can find the game, it's buried somewhere under huge pile of other games, downloaded since then:>)I must say it's one of the best horrors i've played so far(and that's a lot). Atmosphere reminds of "Grave encounters".
Thanks for the compliment! Really appreciate it :)