They refuse to clean and one of the girls said she has a cleaner at home so she will not help with the cleaning, they have mocked and made fun of her accent, they regularly take drugs in the communal kitchen, they use her food and drink out of the fridge and when dd was upset not long after moving in they told her to 'grow up, you're at uni now. go and cry in your room'.
She needs to talk to the Residence service, or the Student Union or Guild, or the University Accommodation Service. I know at my place, bullying behaviour like this is jumped on from a great height.
Is she enjoying her course? The accommodation thing can be solved, so it would be a pity to leave a course she's enjoying because of it.
You say she's shy & introverted. Going home isn't going to help that & she may live lifelong with a sense of failure.
Or she may not be ready for university. Not everybody is, straight out of school. She could finish her First Year, and then take a break - often called either Leave of Absence, or Interruption, or Intercalation. She can get a job & grow a bit in confidence maybe.
But there is help - she should get in touch with her Hall of Residence sub-dean or Residences Service.