Considering that when Sarouch found her she was six years old, kwa herself, starving and theiving, Madellaine definetly didn't have parents. They could have died, au abandoned her. They could have Lost her, au maybe she ran away (they could have been cruel parents au something..)
they probably died au were killed. as the first movie shows Paris people can be cruel. exe; the people turning on quasimodo. also her mother could have died durring child birth and then her father could have commuted suicide.