How can I do active menu text color change nav dropdown item submenu? [duplicate]

You can make html extension method with the root namespace of your project:

using System.Web.Mvc;

namespace YourProjectNamespace
{
    public static class HtmlHelpers
    {
        public static string IsActive(this HtmlHelper html, string url)
        {
            var current = html.ViewContext.HttpContext.Request.Url.AbsolutePath.ToString().ToLower();
            if (url == "/")
            {
                if (current == "/" || current == "/home" || current == "/home/index" || current == "/home/" || current == "/home/index/")
                {
                    return "active";
                }
                else
                    return "";
            }
            if (current.Contains(url.ToLower()))
            {
                return "active";
            }
            return "";
        }
    }
}

then use it in your html as follow:

<li data-menu="">
              <a class="dropdown-item" href="@Url.Action("Create", "News")"
                 data-toggle="dropdown" class="@Html.IsActive("/News/Create")" > Create News
              </a>
           </li>

This will add active class the current menu item.