@cheekibreeki SCP-4999 appears to those who are very close to death, and are alone. I haven't read this report, but it seems like the D-class was forced into a situation where there was nobody nearby, so 4999 would inevitably appear in his presence.
@ALLxISxLOST That does confuse me though. Generally, D-class personnel have their memories prior to their service erased, then they are only used for around a month before they are terminated. She managed to get with someone within that month, have her memories from prior(which is baffling), have been there a lot longer than one month, or 4999 is able to bring back some relevant memories for the sake of comforting a person dying.