It is alleged she lit a fire under a bed in the room she had been sharing with two children on Sunday morning.
More than 160 people were evacuated as fire took hold in the 11-storey Pacific Hotel. No-one was injured.
It came as Australia confirmed two cases of the new coronavirus variant which is prompting new restrictions.
Omicron was first reported by South Africa, and has been classified as "of concern" by the World Health Organization (WHO) with early evidence suggesting a higher re-infection risk.
