try this'
XElement xelement = XElement.Load(@"C:\.........xml");
IEnumerable<XElement> menus = xelement.Elements();
List<string> subMenuList = new List<string>();
foreach (var menu in menus)
{
if (menu.Attribute("id").Value == "......")
{
foreach (var submenu in menu.Elements())
{
subMenuList.Add(submenu.Attribute("name").Value);
}
}
}