A St. Lucie County family is searching for answers after 18-year-old Omari Linzell Williams was struck and killed by a vehicle while walking to get groceries. His family told WPTV they are now calling for changes to make the roadway safer for pedestrians as the traffic homicide investigation continues.Williams' mother, Witney Williams, and aunt, Sharon Garcia, spoke with WPTV reporter Zitlali Solache about the loss and the questions they still h…