The singer/songwriter's official Web site said the dates will likely be rescheduled in August.
Williams bowed out of an appearance Sunday in Charlotte, N.C., just 20 minutes before the doors to the Visulite Theater were due to open, said the Charlotte Observer.
Upon receiving news her mother, 73-year-old Lucille Morgan, died after fighting a prolonged illness, Williams canceled the show to travel to Fayetteville, Ark., to be with her family, Billboard said.
The artist's April Australian tour will go on as planned, as will her two California dates in May.
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