I can see why she wants to keep them in, they're really great cards and can completely turn the game around. That being said, lets look at each individually and see what we can do.
Vampire Nocturnus - Is best when most of your deck is black (which it is). Requires 3 black sources (all of your land produces black) and buffs vamps (which all your creatures are). His only downside is he doesn't stack. If one is in play and you play a second one, its just a 3/3 vamp for 4. Luckily, I have an idea to get around this.
Bloodline Keeper - This card kind of speaks for itself. It spits out tokens and when it flips all your stuff is lethal. Totally a keeper and you want to see one every game. Doesn't fix the problem of getting stuck with multiple in hand waiting for your 4th land drop. I think my idea will help here too.
I think you should add 2 or 3
Olivia, Mobilized for War. This would be a powerful 3 drop flyer that lets you pitch extra cards to give your active dudes Haste and counters. Now if you have 2 Nocturnus in hand, you can pitch one to Olivia to speed up your
Shadow Alley Denizen. But while you're bringing in Olivia, another great card that synergies with it is
Asylum Visitor. Now you can pitch
Asylum Visitor to Olivia, and still play it for Madness cost. Plus the 3/1 body is a real threat, and the possibility of drawing extra cards (which you'll likely do if you're pitching things to Olivia) is a big plus.
To make room for all this, I'd suggest pulling the 2
Merciless Eviction, and the 2
Necropolis Regent, just because your 4 drops are so much more powerful than either of them and making sure you have a strong board state when Nocturnus or Keeper arrives is more important.
I hope you find this helpful and let me know how the deck plays! Seems really cool! Good luck and Happy Hunting