Personally i think that clinic might be the place where Ella met MC, the place where this group of people was and only 2 left... It's speculation of course, but it makes sense on how Ella knew MC used to wear bandages on his eyes...
The father being a government agent might mean that clinic is government funded or related...
It makes sense MC's father has been investigating or at the least has read reports over the years with mysterious deaths, even if just to see if there's similarities to the event involved with his wife's death... The events around town could have alerted him to look around, perhaps he consulted Jeff, perhaps he just stumbled upon him while following his own leads...
Jeff must have been investigating the rise of the Aldain, with the sickly no-use son suddenly appearing as a major player in the war between the Aldains and the Aldermans... Jeff has actively helped Klaus on several occasions to get a seat on the council.
But no doubt he has had reports on Danica, Klaus and Oscar and realised this was no ordinary war... Jeff knows there's more at stake then just some unrest in the world of crime... And even if he wasn't at the start, he had enough reports to suspect supernatural circumstances at a certain point of the investigations.
But that is just the bare minimum, MC's father may have been suspecting X&R for connections to possible supernatural deaths. MC being placed there could be just a convenient move, you never know when you need an insider on that campus...
If the private clinic actually was the place where Ella met MC there is enough reason to assume MC's father has been monitoring Ella too, something that fits being away for almost 2 years, while Ella has been very active these years.
Her name must have come up with the St. Arturius massacre, her name could have linked to the private clinic... And only 2 alive from that time, one being Ella, the other your son? That's alarm bells ringing... Who knows what MC's father learned over the years?
So at what point did MC's father start finding proof of monster involvement? Recently when stumbling upon his old friend Jeff? Around the St. Arturius Massacre? When bringing his son to that clinic? Or even from before the time his wife died?
Was Jeff following up on a lead at the casino? Or perhaps he was there to switch the dead monster with the fairy?
Shady fuckers..... Don't assume they just happen to be there, when you are there for a reason....