Dennett is charged with second-degree murder for the fatal stabbing of Kathleen Livingstone in her Brossard home in the summer of 2011.
Dennett's lawyer, Giuseppe Battista, asked the court to reduce the charge from second-degree murder to manslaughter, arguing that his client was provoked by the victim's comments.
The accused, who had been living with Livingstone for 45 days, previously testified that she was repeatedly picked on by Livingstone and simply could take it anymore.
Defence argues accused was provoked
Dennett told the court on Tuesday she moved back to Canada to be with the victim's son, Robert, after starting an online relationship with him. But Robert moved out of Montreal before she arrived.
Dennett had been living in California, where her adult daughter also resides.
Before the stabbing, Livingstone allegedly told Dennett that her daughter, who is part-hispanic, looks nothing like her.
The court was told by Dennett earlier this week that Livingstone went on to criticize her for leaving her daughter behind to be with Livingstone's "loser" son.
Today, Battista told the court his client was provoked by those comments.
But Crown prosecutor Sacha Blais argued the provocation does not hold up in this case, because similar comments had been made in the past without incident.
Blais said said the comments did not justify losing self-control.
Sam Gaskell, a long-time friend of the elderly woman, said she was offended by the defense's argument.
"Kathy was handicapped, Kathy could not walk and Kathy is dead … Ellen could have walked away," she said.
The judge is expected to release a verdict on March 15.