Mary Fox, 59, died in the fire in Bodmin, Cornwall on Bonfire Night last year after the Silver Dart was thrust inside to "frighten" the family as part of a prank.
Her son Raum, then 17, escaped through a window of the blazing council home in Wallace Road, but his mother inhaled a fatal amount of fumes.
Owen Hewitt 18, and Samuel Luckes, 17, were each jailed for seven years at Truro Crown Court for the manslaughter of the mother of nine. They were also each sentenced to three years concurrently for committing arson being reckless as to whether Raum's life was endangered.
The pair "laughed and joked" that the burning house belonged to Raum's mother, the jury heard earlier.
A third teenager, Ryan Croft, 18, who pleaded guilty at an earlier hearing, was given five years for manslaughter and two years for arson, also running concurrently.
Opening the case to the jury earlier this month prosecutor Paul Dunkels QC said: "On November 5 last year three young men were wandering around Bodmin with a large quantity of fireworks.
"They took a rocket, snapped the stick off it, lit it and put it through the letter box of the home of Mary Fox and her son Raum at 51 Wallace Road.
"It set fire to the house. Raum was able to escape by jumping out of the first floor window. Mary Fox could not get out. She was overcome by fumes and smoke from the fire, and died."
The group did not intend such dire consequences but only wanted to "give the occupants a fright," Mr Dunkels added.
Hewitt, of Bodmin Foyer, Kestenenn and Luckes, of Rhind Street, Bodmin, had pleaded not guilty to the manslaughter of Mrs Fox, and also denied arson.
Croft, of Wallace Road, had earlier admitted both allegations, the jury heard.
Raum had been bullied at school because of his acne and alternative dress sense, Mr Dunkels said. When Mrs Fox escorted him to school that just made the problem worse, he added.
He said: "Raum Fox, 17 at the time, used to be bullied at school. He had bad acne on his face, and used to dress differently to other children.
"Because of the bullying, Mrs Fox used to follow him to and from school.
"Unfortunately, the protection served to mark him out for more bullying - the boy whose mother followed him to and from school.
"At times he would be pushed, struck and verbally abused. That went on until he left in 2008 but continued to some extent afterwards.
"Ryan Croft would shout abuse at him if he saw him in the street.
"Mrs Fox, who could be a little eccentric in her behaviour and appearance, was subjected to verbal abuse by young people who saw her around Berryfields (housing estate)."
He added: "They knew she lived at number 51 and put a firework through the letterbox, knowing that Mrs Fox and/or her son would be inside, intending to frighten them.
"The prosecution say it was chosen because of who lived there."
Unaware of the extent of the blaze, described by local fire crews as the "most intense" they had experienced, the gang went to a firework display, Mr Dunkels said.
But later, he said: "News of the serious nature of the fire was spreading through the town. The three of them were laughing and joking about the fact that it was the house of the woman whose son they used to bully.
"Even though they heard what had happened, they showed complete disregard for the safety of others in the way they used the rest of the fireworks - firing fireworks at each other, and at other people who were around."
Hewitt let off a firework in a telephone kiosk and aimed one at onlookers, he added.
When the three went back to the burned-out house, a female associate commented that it was "brilliant". But Hewitt is said to have remarked that it was not, as "someone could have died".
Some £100 worth of fireworks were bought by Hewitt's stepfather from a supermarket as he was under-age at the time, along with a quantity of alcohol, the court heard.
Made by TNT, they went by the name of Powderkegs, Super Missiles, Shooting Stars, Meteor Shower, Blastermania and Terminator.
Carrying them in his rucksack, Hewitt was allegedly boasting about how many he had as the group drank beer together that evening.
At around 6pm the group went to buy tobacco for Croft's mother, and began "messing around" with the fireworks on the way through the Berryfields estate.
They were challenged by a resident called Mark Broadfield, who asked them if they thought it was funny, to which Hewitt allegedly replied that he did.
After buying the tobacco from a man in the area, they left again, supposedly to go to the firework display.
Passing the Fox home, they lit the firework, snapped off the stick and pushed it through the letterbox, "their intention plainly being to frighten the occupants", Mr Dunkels said.
Raum, who was in his bedroom, smelled smoke and saw it coming into his room across the ceiling.
Describing the scene, Mr Dunkels said: "He realised he couldn't get downstairs from the landing. The fire was already well advanced by then.
"He went to his mother's bedroom and got her out. She tried to go downstairs but was beaten back by the smoke so he led her into his bedroom.
"Raum found it difficult to breathe. He crouched down to try to get beneath the smoke. He opened the window, telling his mother that he was going to jump out to get help."
Down in the garden he shouted at his mother to jump, and alerted the neighbours.
But Mrs Fox, who was not agile, did not jump, and was later found to have died from the inhalation of smoke and toxic gases.
Neighbour Gary Holt tried to get Raum away from the flames, while a passer-by, Anthony Kelly, went to the hallway "but was beaten back by the ferocity of the flames", Mr Dunkels said.
Luckes at first told police he was not around at the time, while Hewitt is said to have changed his story several times, at one stage saying it was the others who had gone into the garden.
The prosecution said it was a "joint enterprise" and, although they did not intend to destroy the house, they wanted to to scare the Fox family.
