When inside, Wallace was disturbed by the elderly woman, and told her he was looking for someone before he left the house with a wallet.
Wallace then returned to the house a few hours later, when the elderly couple were asleep.
Judge Davidson said the elderly woman woke up and disturbed Wallace once again, before he assaulted her, and her husband.
"Details of the assault are scant but it is clear both were knocked unconscious."
Judge Davidson said the man suffered from facial fracture and bruising, and the woman had cuts and brain swelling.
The pair were hospitalised after the attack and had since moved to a retirement home, Judge Davidson said.
"To say both the occupants had been badly affected is really an understatement.
"You stripped them of their independence, something which is tremendously valued by elderly people."
Judge Davidson said the couple were entitled to live the later part of their life peacefully.
Crown prosecutor Ian Murray said it was "without a doubt a very serious and troubling offending".
Mr Murray said Wallace had quickly resorted to very serious violence.
However, defence lawyer Janine Bonifant said Wallace was remorseful of his actions.
"Mr Wallace has accepted from the outset all the matters."
She said Wallace was supported in court by his grandmother and aunt, as well as other members of his family, who sat in the public gallery. His mother was unable to attend.
Judge Davidson sentenced Wallace to five years and nine months in prison.
As Wallace left the court room, a member of his family called out to him that his mum "loved him".
