Question: Who laced the cookies that were given to the children with arsenic? It's never shown who applies it, only who takes the cookies to them.
Question: I saw this movie for the first time in years the other night, and I did not remember that Nancy was killed in this one. Is this the last nightmare film that she was in (other than the one where Freddy came to the real world and everybody played real names)?
Answer: Yes it is the last one.
Answer: Technically she was also in New Nightmare, both as the "Nancy" character and as the actress Heather in various scenes.
Technically the author said other than the one where Freddy came to the real world and everybody played real names. So therefore the 1st answer was accurate.
Answer: When the children discover the cookies had been poisoned (revealed by the death of their pet mouse which ate part of one of the cookies), they suspect their grandmother. After all, she was the one who had been cruel to them all along. But eventually, they realise that it was in fact, their mother, Corinne, who was lacing the cookies with poison. She was doing so with the hope that the children would eventually die, seemingly from disease. In doing so, she would secure the family inheritance which was contingent upon her never having had children from her first marriage. They eventually confront their mother on the day of her second wedding, and a struggle ensues which ultimately leads to Corinne falling to her death from a balcony.
Michael Albert