Hello , i found this example online and its working

   var i = new Umbraco.Web.Models.Trees.MenuItem("duplicateNode", "Duplicate");
                        //optional, if you dont want to follow conventions, but do want to use a angular view
                        i.AdditionalData.Add("actionView", "/App_Plugins/DuplicateNode/DuplicateNodeView.html");
                        i.Icon = "user-females-alt";

                        //insert at index 5
                        if (e.Menu.Items.Count > 5)
                        {
                            e.Menu.Items.Insert(5, i);
                        }

i had tow Cases:

1-what if i want to show it only for a specific user orset of users.

2-what if u want to show it only for a specific document type.