John Bathers, 80, died in hospital on September 8, after suffering head injuries at his home in Oak Drive, St Martins, two days earlier, Stafford Crown Court heard.
Mr Robert Price, prosecuting, said his grandson Ashley Sumner, 31, had gone to visit the pensioner, who was physically frail and unsteady on his feet, on September 6.
The court heard Mr Bathers had a number of health problems, suffered back-to-back chest infections and had in the past had four heart bypass operations.
Mr Price said when Sumner visited on September 6 the pair had an argument over how Mr Bathers was going to distribute money in his will.
He said: "He'd made alterations to his will in the months leading up to his death. The defendant wasn't happy about the alterations he had made."
During his grandson's visit, Mr Bathers had taken a phone call from his daughter – Mr Sumner's mother – and explained the pair had argued over money.
She heard Sumner in the background "gobbing off about money".
Mr Price said Mr Bathers had taken hold of Sumner's arm, who tried to shake free causing his grandfather to lose his balance, fall and hit his head.
He was later taken to hospital but died after suffering a brain hemorrhage.
The court heard that following the argument with his grandfather, Sumner took Mr Bathers car without his permission and returned it a day later.
Mr Price said in general their relationship had been good and they had been close, but when Sumner drank alcohol it caused him on occasions to be aggressive and argumentative.
Although, there was no evidence he had been drinking before the argument with his grandfather.
He said Mr Bathers' death left Sumner's mother "heartbroken" and "devastated".
In a victim personal statement, she said: "My life feels like it's ruined. I don't want to face the world.
"I've not just lost my father – the man who always looked out for me, who protected and loved me, but I've lost my son.
"My father was my everything, my world, my hero. I'm 49 and still if I was struggling with anything in life or if I was poorly I always wanted my father.
"When my mother passed away nearly three years ago I made a promise to her and to my father that I would always be there for him.
"I did his washing, cooking, cleaning, paperwork and shopping. Nothing was too much because he was my world. My life without him will never be the same."
Sumner, of Berwyn View, Ellesmere, previously admitted the unlawful killing of Mr Bathers, taking his grandfather's Honda Jazz without consent on September 6, and driving the same vehicle other than in accordance with a licence and without insurance.
Ms Lynette McClement, representing Sumner, said he had always known he was not in his grandfather's will and the argument was over the fact Sumner felt his mother would not receive the money his grandmother intended her to have.
She said Sumner often went to see his grandfather when he needed someone to talk to and he had lived with his grandparents growing up.
Ms McClement said they had a close bond and Sumner was "devastated" by what happened and he had not realised how serious his grandfather was injured.
The court heard he took Mr Bathers car to a shop to buy alcohol and left the car there until returning it the next day.
Mrs Justice May DBE sentenced him to three years in jail for manslaughter, and gave him no separate penalty for the other offences.
Sumner wept as she told him: "You both had a very good relationship, of all his grandchildren you were the one who would come round when asked and do tasks around the house which makes this episode so much more sad and shameful.
"You didn't mean to cause his death, nevertheless in your anger that's what you did.
"You will have to find a way to live with that, to make your peace with it and to go on and make him proud of you as he would have wished."
A statement released on behalf of Mr Bathers' family following his death said: "We are deeply saddened by the loss of our beloved dad, grandad and great grandad.
"We will remember him as a kind and caring man who was dearly loved by his family. We will miss him deeply and he will always be in our hearts."