A single-car crash sent four people to the hospital last night in Mililani.  It happened just before 10 p.m. Friday when a car crashed into a treet on Lanikuhana Avenue and Makaimoimo Street.  Emergency Medical Services reports paramedics took a 71-year-old woman, a 20-year-old woman and 20-year-old man and a nine-year-old boy to a trauma center.  All of the patients were in serious condition.