Barnabas is concerned about Elizabeth, but I don't think he's feeling any human emotions. At this point, he wants her to live so he can stay in the Old House. He tells her, I don't usually get involved in the affairs of other people. it's pretty clear that he's only looking out for his own interests.
When Barnabas brings Elizabeth back to Collinwood, David calls to her cheerfully, but she ignores him completely--a sure sign that something is horribly wrong.
Fun conversation between Barn and David! We now have a few clues as to why the terrible, unhuman vampire talks to children with such ease. Barnabas starts when David tells him that Sarah sings "London Bridge," but he manages to conceal it and tells David, You're quite a young modern man! Well, if you do see her, tell her not to play at the Old House. I’m not allowed to play near the Old House, David answers primly--winning this round!--and heads for the kitchen.
When Barnabas goes to see Vicki, we hear a bit of "London Bridge" even though Sarah is nowhere nearby--music blooper?
Vicki tells Barnabas that she's having dinner with Burke. Evidently the idea of even a potential rival hadn’t occurred to Barnabas, because Burke’s name stops him in his tracks and gives him his second shock in less than ten minutes.
Apparently Burke doesn't come to the Great House to pick Vicki up for dinner. And later, she rushes out of the BW despite his protests. Thus Vicki has come into town alone and returned to Collinwood alone, completely disregarding the curfew that has been imposed on the town.
I have to wonder what Barn thinks of 20th-century dating rituals, so different from the courtship rituals and arranged marriages he knew way back when. You can take the vampire out of the 18th century, but you can't take the 18th century out of the vampire!