Sylvia Ann Stevenson, 49, whose own 12-year-old son was seriously injured in the crash was also banned from driving for a year.
Judge Kevin Finnegan QC told Ms Stevenson that while the period of her inattention was short, less then two seconds, "the consequences were enormous".
Stevenson from Riverdale, Kilkeel, admitted causing the death of Kevin McEvoy by her undue care and attention whilst driving along the Newry to Kilkeel road on 16 August, 2011.
The Newry Crown Court judge said that apart from the tragic death of Mr McEvoy, the only aggravating feature put forward were the extensive injuries to Stevenson's own son who suffered a ruptured spleen.
Judge Finnegan said that this was an added punishment for her to bear and he had no doubt that this and the fact her careless driving caused a pensioner's death, "will remain with her for the rest of her days".
Judge Finnegan said the death of Mr McEvoy was not forgotten by the court, which offered its sympathy, but it was often said that no sentence or punishment could restore a human life, nor could it, or was it intended to express, or measure the worth of that life.
As to the cause of the accident, the judge said of the three theories put forward, the first, that Stevenson was momentarily distracted by an exchange of words with her son, was probably the most accurate, although no definitive cause was put forward by either the prosecution or the defence.
Prosecution lawyer Geraldine McCullough had told an earlier hearing of the court that Stevenson's black Nissan Quasqui 4x4 had smashed head-long into Mr McEvoy's Toyota Aventis, which was then forced into the front of a Volkswagen Sharan, with a mother a daughter, and niece, heading to the airport to send off another daughter to Australia.
Those plans were thrown into disarray, although luckily one of the women was an off-duty policewoman, who immediately took control of the situation, and with another passer-by, administered CPR.
However, their efforts, and those of the emergency services, to resuscitate Mr McEvoy from Glenloughran Road, Kilkeel, failed.
Ms McCullough also told the court that when initially spoken to, Stevenson claimed "there had been a head-on collision up the road", but that there had been no such accident "or any obstruction in the path of the defendant's vehicle".
The prosecution lawyer also revealed that it was the women in the Volkswagen, who were able to "provide the evidence of what occurred at the scene."
Ms McCullough said the driver of the Volkswagen described how as Stevenson's 'jeep' drove down the road, "it suddenly pulled across the road" and into the path of Mr McEvoy's Toyota ... "no more than a few feet away from us..."
"There was no obstruction in the roadway either on the jeep's side of the road, or ours, and I don't know why she pulled over onto our side so suddenly," said the lawyer, reading from a statement.
A split second later, the driver screamed a warning to her mother and passengers as she slammed on the brakes, only for Mr McEvoy's Toyota to smash into the front of her car, such was the force of impact from Stevenson's 4x4.
Defence lawyer Michael Duffy said that the family of Mr McEvoy were clearly upset by his death and the apparent indifference of Stevenson, but that he wanted to reassure them nothing was further from the truth.
The lawyer revealed that Stevenson had wanted to approach or even write to them to express her remorse, but had not done so on his advice.
Mr Duffy also admitted that her partner had wanted to attended the funeral, but again on legal advice, had not done so.
Stevenson, he added, was remorseful and disturbed at the consequences of her actions, and that level and depth of remorse could be seen from the pre-sentence report on her.
Stevenson, said Mr Duffy, had co-operated fully with police and was a person of good character, with no previous criminal record.