Karen Corr - a 55-year-old Neighbourhood Support Officer with Wolverhampton Council - and Wolverhampton Homes Estates Manager Joanne Lewis, aged 51, deliberately targeted frail John Addison.
Over the next two years they syphoned around £72,000 from his bank accounts in cash and cheques which were written by them and signed by their confused victim, the city's Crown Court heard.
Money was switched to accounts from which it could be easily withdrawn.
The conniving couple posed as the man's nieces, acquired power of attorney to control his finances in January 2015 and managed to trick him into to change his will to make them his sole beneficiaries, revealed Mr Nigel Stelling, prosecuting.
They knew the victim had a further £98,000, £75,000 of which was still in a bank account already plundered by the duo and kept secret from officials by them so it would not be spent on his welfare in the care home to which he was moved in 2016 after several hospital admissions.
They even sold his cooker when he was moved from his Wolverhampton home.
Mr Addison first fell into their clutches in 2014 while living alone when Wolverhampton Homes were alerted to the fact he needed a tree cut down.
The case was passed to Lewis and when a GP alerted the authorities to the elderly man's increasing inability to live alone she referred the matter to Corr.
The two women left instructions with the care home banning visits from his former neighbours who were also denied any information about his health.
The addition of 'Do Not Resuscitate' to his records was sanctioned by Corr, continued Mr Stelling who said the pair had 'cynically and systematically' preyed on the man.
A text message between them read 'Big money. Whoop, whoop.'
Another sent while he was in hospital said: 'Need to get more money out before the inevitable.'
Their shameful behaviour was disclosed after an anonymous call from a former neighbour of the victim in July 2016 prompted a police investigation which resulted in the arrest of both women.
The prosecution were unable to explain what happened to the missing money.
Mr Gurdeep Garcha, defending, insisted: "It was not spent on high living."
Corr of Sandy Lane, Bushbury and Lewis from Victoria Road, Wednesfield each admitted conspiracy to defraud by abuse of position between September 2014 and August 2016.
Mr Addison, now in his 90s, is not well enough to realise he has been fleeced.