An elegy is a type of poem that typically is a lament for the dead. Based on this definition, it is very hard to come up with any way whatsoever in which this poem could be seen as an elegy. By contrast, it is a violent attack on the speaker's father, and a resurrection of sorts before a final burial and a triumph over the dead body of the speaker's father. Note how this is achieved in the final verse:
There's a stake in your fat black heart
And the villagers never liked you.
They are dancing and stamping on you.
They always knew it was you.
Daddy, daddy, you bastard, I'm through.
The use of the word "bastard" in the final line shows the intensity of the speaker's emotion as she culminates this attack on her father with a recognition of how cathartic this frenzy of words and emotion has been for her. The comparison of her father to a vampire in this final stanza likewise helps the speaker finally finish with him, as she is able to say that "There's a stake in your fat black heart." Traditionally, one way of killing vampires was to put a stake in their hearts. The figure of the speaker's father, who still haunts his daughter after his death in a way that is reminiscent of undead beings, now is finally put to rest. This poem therefore can only be described as a perverted elegy, that does not mourn, but celebrate, the passing of the speaker's father.