Saffie Roussos, 8, from Leyland in Lancashire, was among the 22 people killed by suicide bomber Salman Abedi at Manchester Arena.
She had been attending the Ariana Grande concert with her mum, Lisa, and older sister Ashlee Bromwich.
Lisa and Ashlee, who is in her 20s, were both taken to hospital.
In a post on Facebook group Leyland Memories, Mike Swanny said he could confirm the “amazing news” that Lisa Roussos was “awake and out of surgery”.
Mrs Roussos was apparently in a critical situation at first, but came off life support on Saturday.
Mr Swanny said she was “talking, and is fully aware of the situation”, adding that she was “now out of any danger”.
He added that Ms Bromwich was also improving and had been talking to her mum.
Mr Swanny finished by saying: “I hope this news will make everyone smile as this is the best news we’ve had through this tragedy.”