Is the wife obligated to wash her deceased husband before the washers enter, and is this act a Sunnah, an obligation, or an innovation?

If a Muslim dies, those present must wash and prepare the body. The washing should be done first with pure water, then with water and sidr (lote tree leaves), and then with water and camphor (or perfume). This washing is the same whether performed by the wife or someone else. However, she is not obligated to wash him if someone else is available to do so on her behalf.