Heroin addict Mark Mills also stole a bank card from a woman aged 81.
Hamilton Sheriff Court heard last Friday that she hit Mills with her walking stick in an effort to get him out of her home.
Mills, 27, of Watson Street, Motherwell, was jailed for 30 months when he admitted charges of robbery and theft.
Jennifer Cunningham, prosecuting, said the 94-year-old lives alone and has poor eyesight and hearing. Mills went to her home in Mason Lane in the afternoon of February 7 this year.
Ms Cunningham told the court: " She opened the door and the accused asked her if she was Mrs Aitken as he had a milk delivery for her. She said no and he barged past her, pushing her aside. Mills made his way to the living room. She saw him rummage through a chest of drawers and told him she would phone the police.
"The accused stood up and shouted 'I want money' and refused to leave. She said she would give him whatever he needed and her purse was in the kitchen.
"The accused ushered her into the kitchen and stood at the back door, blocking her exit and making her feel trapped. The woman opened her purse and the accused grabbed two £10 notes before casually leaving.
Police were alerted and officers found the old woman "visibly distressed".
CCTV footage pointed to Mills but he struck again four days later before being arrested. This time he targeted a pensioner at a bungalow in Coursington Gardens where homes for elderly and other vulnerable people are located.
He turned up at the 81-year-old's home at lunchtime on February 11 -and rifled through drawers until he found a bank card. Her back door was slightly open to let her dog in and out. Mills admitted using her bank card at a nearby shop 20 minutes later.
Passing sentence, Sheriff David Young said Mills had targeted vulnerable people and the court had to "show society's displeasure".
The 30-month sentence was reduced from 40 months because of his guilty pleas and backdated to February 12 as he has been in custody since then.