A judge who sentenced James Osborne said the 32-year-old had shown “not one jot” of remorse over the attack.
Osborne bit his father and threatened to hit his mother during the incident at the family home in Hazel Road, Knottingley.
Leeds Crown Court heard Osborne and his partner, Louisa Hall, 36, were homeless and had drug problems but had been allowed to live in a tent at the back of his parents’ home.
James Gelsthorpe, prosecuting, said Osborne became aggressive after going to the house and demanding money from his mother. She refused so Osborne threw a concrete slab through the window.
He then climbed into the house and threatened to hit her with a stick. Osborne’s father and brother arrived and he picked up a shard of glass.
Osborne’s father managed to get his son into a headlock but he was bitten on the finger. Hall also entered the house and shouted encouragement to her boyfriend and was involved in a struggle with Mrs Osborne.
Osborne took a bag of change worth £20 before the couple left. Osborne and Hall returned to the house later while Mr Osborne was in hospital receiving treatment for the bite injury.
The pair forced their way in and Mrs Osborne was pushed into the living room by her son. He took £200 from her purse.
Osborne pleaded guilty to robbery, attempted robbery and theft. Hall pleaded guilty to affray and was jailed for 22 months.
Mr Gelsthorpe read a victim statement to the court on behalf of Mr Osborne in which he stated: “I can’t believe that he came back and stole from his mother while I was in hospital.”