PHP自动完成错误的编码输出

Question

I have been trying to make an autocomplete (datas fetched from database), and although I am having a problem with the encoding when I am clicking to the searchbar , it shows the places names in a bad encoding

Codes below:

---

$autocomplete= $db->query("
  SELECT DISTINCT Helyseg FROM M_munka 
  WHERE
    Publikus = '1' AND
    Aktiv = 1 AND
    Jovahagyott = 1 AND
    Helyseg!='null'      
");
$autocomp_q= $autocomplete->json();
$json = json_encode($autocomp_q);

---

function fetchAllArray(){
      $Data = array(); 
      if( !$this->is_empty() ){
          $this->reset();
          while($row = mysqli_fetch_assoc($this->result)){
               $ata[] = array_map('htmlentities',$row);

          }
      }
      return $Data;
  }

   function json(){
      $Data = $this->fetchAllArray();
      return json_encode($Data);
    }

---

$(function () {
  //$json fájl - json_encoding data 
  var availableData = <?php echo $json;?>;
 var myObject = JSON.parse(availableData);


    $('#tags').autocomplete({
        source: function (request, response) {
            var re = $.ui.autocomplete.escapeRegex(request.term);
            var matcher = new RegExp("^" + re, "i");
            response($.grep(($.map(myObject, function (v, i) {

                return {
                    label: v.Helyseg,
                    value: v.Helyseg
                };
            })), function (item) {
                return matcher.test(item.label);

            }))

        }
    });
});

My guess is that it's the JSON.PARSER which ruins the encoding (picture result below).