Problema com lógica para preencher um html dinamicamente

public ActionResult PaginaBaseMenu(int Parametro)
        {
            AgaxturCmsEntities db = new AgaxturCmsEntities();
            int _parametro = Parametro;
            try
            { 
                var menu_sup = (from rc in db.TB_MENUSUPERIOR
                                join c in db.TB_MENUSUPERIOR_CATEGORIAS on rc.Id_Categoria equals (c.id)
                                join s in db.TB_MENUSUPERIOR_SUBCATEGORIAS on rc.Id_SubCategoria equals (s.id)
                                join s2 in db.TB_MENUSUPERIOR_SUBCATEGORIAS2 on rc.Id_SubCategoria2 equals (s2.id)
                                where rc.Ativo == 1 && rc.Cdcliente == 1 && rc.Id_Categoria == _parametro
                                select new
                                {
                                    Conteudo = rc.Conteudo
                                }).FirstOrDefault();
                ViewData["htmlBaseMenu"] = menu_sup.Conteudo;
                return View();
            }
            catch (Exception ex)
            {
                string e = ex.Message;
            }
            return View();        
        }

[HttpPost]
        public JsonResult MontaMenuSuperiorDestino()
        {
            AgaxturCmsEntities db = new AgaxturCmsEntities();
            try
            {
                var resultado =
                    (from c in db.TB_MENUSUPERIOR_CATEGORIAS
                     //join s in db.TB_MENUSUPERIOR on c.id equals (s.Id_Categoria)
                     //join s2 in db.TB_MENUSUPERIOR_SUBCATEGORIAS2 on s.id equals(s2.Id_SubCategoria)
                     where c.Ativo == 1 && c.CdCliente == 1
                     select new
                     {
                         c.id,
                         c.Categoria,
                         cont = (from rc in db.TB_MENUSUPERIOR
                                            join cat in db.TB_MENUSUPERIOR_CATEGORIAS on rc.Id_Categoria equals(c.id)
                                            //join s in db.TB_MENUSUPERIOR_SUBCATEGORIAS on rc.Id_SubCategoria equals(s.id)
                                            //join s2 in db.TB_MENUSUPERIOR_SUBCATEGORIAS2 on rc.Id_SubCategoria2 equals(s2.id) 
                                            where rc.Ativo == 1 && rc.Cdcliente == 1
                                            select new { 
                                                rc.Conteudo,
                                                rc.Id_Categoria,
                                                rc.Id_SubCategoria2
                                            }).ToList(),
                         subconsulta = (from sub in db.TB_MENUSUPERIOR_SUBCATEGORIAS
                                        where sub.Ativo == 1 && sub.CdCliente == 1 && sub.Id_Categoria == c.id
                                        select new
                                        {
                                            sub.Id_Categoria,
                                            sub.SubCategoria,
                                            subconsulta2 = (from sub2 in db.TB_MENUSUPERIOR_SUBCATEGORIAS2
                                                            where sub2.Ativo == 1 && sub2.CdCliente == 1 && sub2.Id_SubCategoria == sub.id
                                                            select new { sub2.Id_SubCategoria, sub2.SubCategoria2 }
                                                ).ToList()
                                        }
                                        ).ToList(),
                     }).ToList();
                return Json(new { resultado }, JsonRequestBehavior.AllowGet);
            }
            catch (Exception ex)
            {
                return Json(new { resultado = ex.Message }, JsonRequestBehavior.AllowGet);
            }
        }

@(new HtmlString(ViewData["htmlBaseMenu"].ToString()))

function MontaMenuSuperiorDestino() {

    var str = "",
        _conteudo = "";
    var id_cat = 0,
        idx = 0,
        id_cat = 0,
        id_sub2 = 0;

    $.ajax({
        url: '/Home/MontaMenuSuperiorDestino',
        dataType: "json",
        contentType: "application/json; charset=utf-8",
        type: "POST",
        success: function (data) {
            $(data.resultado).each(function () {
                //str = str + '<li><a href="#" title="">' + this.Categoria + '</a><div class="container_24 dropdown-menu">';
                idx = this.id;
                $(this.cont).each(function () {
                    id_cat = this.Id_Categoria;
                    id_sub2 = this.Id_SubCategoria2;
                    _conteudo = this.Conteudo;                    
                });
                if (id_cat == idx && id_sub2 == null) 
                    str = str + '<li><a href="Home/PaginaBaseMenu/' + id_cat + '"title="">' + _conteudo + '</a><div class="container_24 dropdown-menu">';
                else
                    str = str + '<li><a href="#" title="">' + this.Categoria + '</a><div class="container_24 dropdown-menu">';
                $(this.subconsulta).each(function () {
                    str = str + '<ul class="grid_4"><li>' + this.SubCategoria + '</li>';
                    $(this.subconsulta2).each(function () {
                        if (id_sub2 > 0)
                            str = str + '<li><a href="Home/PaginaBaseMenu/' + id_sub2 + '" title="">' + this.SubCategoria2 + '</a></li>';
                    });
                    str = str + '</ul>';
                });                
                str = str + '</div></li>';               
                $("#menuheader").append(str);
                str = "";
            });
        },
        error: function (error) {
        }
    });
}