okay,a bit more info...she remembers that there was a blood transfusion,but not sure who got it,and that there are several scenes in a disco club...i know,not much help,sorry!
Could it have been Grave of The Vampire
from the early 70's, given the timeline we're speaking of? The guy was a half-human\half vampire offspring of Dracula.
There was no transfusion in that movie, but a scene where the half-vampire (as an infant) is being fed blood thru a baby bottle as him mom draws it from her arm with a needle.
Later, this woman was in love with the vampire and I believe there was a song in there somewhere.