Judith Davis, from Pitmedden, said a picture of Hannah, who has Pfeiffer syndrome, was doctored and shared by pupils who attend Meldrum Academy.
One showed Hannah in her wheelchair on a motorway, with an insulting comment.
Aberdeenshire Council said the school had spoken with parents of the children who had created the content.
In a statement, the local authority added that it took allegations of bullying extremely seriously.
However, Mrs Davis believed the kind of cruelty her daughter had been put through was not being taken seriously enough.
Hannah was born with a rare genetic condition in which the skull does not form properly.
Her first year of life was spent in hospital, she uses a wheelchair and has had five major surgeries on her skull, with the prospect of another one soon.
Mrs Davis explained that the distasteful images – which the BBC website has chosen not to show – came to light when Hannah’s older sister, who attends Meldrum Academy, received them online.
One picture showed the youngster lying in a disabled parking space; another had superimposed her onto a movie poster and the third was of Hannah on a motorway.
Mrs Davis said: “They had taken Hannah’s body out of a picture and superimposed that. I cried.
“We were shocked, it’s not the first time it’s happened, it happened last year, the pictures last year weren’t quite as bad.
“But we were absolutely horrified that she was being laughed at, because there’s absolutely nothing funny about having the situation that she has. They probably don’t appreciate the half of it.”
The family reported the matter to both the police and the school on May 2.
Police Scotland said officers “immediately” contacted the school and the pupils who had made the content were identified.
Insp Andy Scott added that after a “thorough review of the circumstances” it was decided appropriate action would be “led by the school itself”.
He told BBC Scotland “Our approach was explained to all those involved including the complainer and updates provided throughout, however we would be more than happy to speak with her again if this would assist in alleviating any of her concerns.
“Police Scotland is committed to working with our partners to protect members of the public whilst online and supporting schools to ensure young people know that their actions in the virtual world can have severe consequences.”
Mrs Davis said she was aware the parents of the pupils had been spoken to but that the offensive images had not been produced during school time.
She continued: “When I was at school, whether you did it at school or out of school, you were a pupil at that school and anything you did reflected on your school.
“I don’t know what the parents have done about it. I don’t feel that just a parental punishment is enough. There’s no deterrent. Getting a row from your mum and dad for me is not enough. I would like it to be taken more seriously.
“They are not learning that being cruel to disabled people is wrong.”
Hannah’s mother said the episode had taken a “massive toll” on the family.
“We have got enough to deal with, life’s really hard as it it without other folk finding it amusing,” she said.
As well as confirming that the school was aware of the matter, Aberdeenshire Council said that in “general terms” school assemblies, content in the curriculum and after school activities were used to tackle anti-bullying and staying safe online.
Its statement added: “Any parent who has a concern should raise it with the school as soon as possible.”