{
  "results": [
    {
      "id": 1,
      "text": "Option 1"
    },
    {
      "id": 2,
      "text": "Option 2"
    }
  ],
}

public class Select2
{
    public int id { get; set; }
    public string text { get; set; }
}

[HttpGet]
        public async Task<ActionResult> GetMesa(string q)
        {
            try
            {
                if (String.IsNullOrEmpty(q) || String.IsNullOrWhiteSpace(q))
                {
                    return Json(new { });
                }
                else
                {
                    List<Mesa> mesas = await db.Mesa.Where(x => x.NombreMesa.ToLower().StartsWith(q.ToLower())).ToListAsync();
                    List<Select2> items = new List<Select2>();
                    foreach(var mesa in mesas)
                    {
                        Select2 item = new Select2() {
                            id = mesa.MesaID,
                            text = mesa.NombreMesa
                        };
                        items.Add(item);
                    }
                    return Json(new { items = items },JsonRequestBehavior.AllowGet);
                }
            }
            catch (Exception e)
            {
                return Json(new {respuesta = "MesasController => GetMesa n" + e.Message + e.InnerException});
            }
        }