In a large bowl, combine the sugar, flour, nutmeg, lemon zest, salt, rhubarb and peaches. Transfer to a greased 11x7-in. baking dish. , In a small bowl, combine the flour, oats, brown sugar, cinnamon and salt. Cut in butter until mixture resembles coarse crumbs; sprinkle over fruit. Bake at 375° for 30-35 minutes or until bubbly and fruit is tender. Serve warm or cold.