The woman, aged 88, had given the group glasses of water after they asked for some around 10pm.
Shortly afterward they came back to the house, but were asked to leave.
Detective Senior Sergeant Roger Small said two girls in the group smashed the woman's front windows in retaliation.
The victim then called a neighbour who helped the woman place a couch up against the window to secure her property overnight.
The woman then went to bed but was woken by a smoke alarm as her couch went up in flames.
She was uninjured and firefighters put out the blaze.
Small said police were making enquiries to identify others allegedly involved in the incident.
Police would like to thank the community and the media for assisting in the matter.
