Grace Whitehead says her terrified daughter Nellie Nwazi, aged 24, and two granddaughters Bloom, six, and Charlotte, three, were snatched from their home on Hastliar Road South, Woodthorpe, in the early hours by immigration officers.
The family, who have been in Sheffield for three years, have been taken to a detention centre in Bedford and are due to be deported to their native Malawi next Friday.
The little girls, who both attend Stradbroke Primary School, speak only English and not the native Malawi tongue, Chichewa.
Today their grandmother, with Nellie's boyfriend Chris Tavernor, 26, from Handsworth, told The Star they fear for the family's safety if they are forced to leave the UK.
Grace said: "Malawi is a dry country. They will die if they go there. They will starve. They haven't got any help. They only have me, I am the only person who can help them.
"Why are they sending them away? I can't send all the food that they need there.
"Nellie has no family there, no job, no house and no help. They don't even have any blankets."
Grace - who is also from Malawi but now lives in Sheffield legally after marrying city man Michael Whitehead six years ago - said immigration officials arrived in the middle of the night.
"They were banging on the door," she said. "They almost broke it down. They didn't allow them even to take warm clothes or blankets. They left the house a mess.
"The children are scared in the detention centre. They don't know where they are or what is going to happen to them."
Nellie, Bloom and Charlotte's forced removal from Sheffield followed the failure of a three-year legal battle for asylum status to allow them to remain in this country.
Grace married Michael Whitehead, now the landlord of The Sheaf House pub on Bramall Lane, in Malawi in 2000. They moved to Sheffield and she became a British citizen.
But when Grace's mother died in Malawi in 2003, Nellie and her daughters were left with no form of support so Grace brought them to