Not this Menu, it works with "using UnityEngine;", it's allready declared on his screenshot
Maybe u should try to work with the menu, without renaming it, work with UnityModMenuAndroid: to learn how the menu works correctly.
@Tigress is MyGUI your OnGUI Method ?
if yes, it should look like this ! did u reload the files ? update ? after u added the menu code ?
public void OnGUI()
{
UnityModMenuAndroid.OnGUI();
}