An 88-year-old woman and her 49-year-old son were among three people rushed to area hospitals following a harrowing collision that caused one vehicle to flip over. Officials said that a Toyota Sienna minivan was traveling past the corner of Nostrand Avenue and Avenue R at 3 p.m. on Oct. 27 when it was struck by a black Mercedes. The force of the impact sent the Sienna, which carried Kings Highway resident Roman Sher and his elderly mother, tumbling onto its roof. Paramedics took Sher, his mother and the driver of the Mercedes to area hospitals, where they were all listed in stable condition following treatment. Cops were still investigating the cause of the accident late Monday.