Linda Kennedy, 58, was told to either move to a smaller home or take in a lodger when the benefit cut increased her rent by £100 per month.
Mrs Kennedy, from Glasgow, who receives housing benefit and a pension of £72.07 a week from her late husband's employer, said she was unable to meet the increase.
Her daughter, Lyndsay Ferry, appeared before the Scottish Parliament Welfare Reform Committee to explain how the 'bedroom tax' had affected her mother.
She said her parents had both always worked until six years ago when her mum became full-time carer for her dad, who has since died.
Since her children left home Mrs Kennedy now lives alone in a three-bedroom house.
She said: "I have lost everything, my husband and now possibly my home."
Ms Ferry, who is expecting a child, said instead of watching her mother lose her home, she and her brother are helping her meet the shortfall in rent.
Mrs Kennedy received a Discretionary Housing Payment for three months, but was then told either to move, or take in a lodger.
The committee also heard from Anne Bradley, from Glasgow, who said she had been given 24 hours to accept an offer of a one-bedroom flat, after also being told to move or take in a lodger.
She moved, but said she had to rely on her family to help pay for moving costs.
She told the committee she first read about the 'bedroom tax' in the Evening Times.
She said: "The increase was £43.64 a month for me. After bills, there's not that much left.
"I had no choice. I was forced to accept, but I have become isolated since moving.
"Before, I met and spoke to people every day. Now, since I moved, I have not spoken to a single person."
Scott Wilson from Biggar, South Lanarkshire, told the committee he had to give up his gardening business and job as a retained firefighter when diagnosed with early onset Parkinson's disease.
He said he has been told to move from the house that the council adapted for his needs if he can't pay the rent due to the 'bedroom tax'.
Michael McMahon MSP, committee convenor, said: "It is beyond me that a Government that has a benefit system providing the minimum level to subsist then brings in a policy to take 14% or 25% from the minimum, putting people below the breadline. That is not a benefit system that is a valid one."