Andrew Den-Drijver, 28, was twice the drink-drive limit when his Renault Megane careered on to the pavement of Jubilee Avenue and killed 51-year-old Janice Buckland on January 24 last year.
He was sentenced to five years and two months in prison at Northampton Crown Court last month, of which he will serve half.
But Janice’s daughter Lisa says the jail term is too lenient – and the family will be appealing.
She said: “He took my mum away and took my whole life away, she was always there whenever I needed her.
“Knowing that he will be out in just over two and a half years and free to be with his family is a real kick in the teeth.
“We were told not to appeal by our barrister, who works for the Crown Prosecution Service, but we will be.
“If he actually had to spend five years in prison I would be more happy.
“He got to spend Christmas with his family but my mum’s grandchildren will never seen their nan again.“
After being arrested Den-Drijver was breathalysed and gave a reading of 81mcg of alcohol in 100ml of breath. The legal limit is 35.
He admitted that he had been drinking beer and vodka until 3am on the day but thought he was “fine to drive”.
Lisa says one of the hardest things to take was seeing him drive after killing her mum.
She added: “They wouldn’t take his licence from him because he hadn’t appeared at the magistrates court but that didn’t happen until nearly nine months after the incident.
“The hardest thing was watching him leave court and drive off.
“He only lived a 10-minute walk from my mum’s house so he drove past there all the time and it was tough to take.
“The whole process and the way the CPS have gone about it has seriously disappointed me.
“My mum was on the path and doing nothing wrong, she was innocent.
“Five years is just not enough.”