Prepare Pastry for Single-Crust Pie. Preheat oven to 400°. For filling: In a large bowl, combine 11/2 cups sugar, 1/4 cup flour and the nutmeg. Add the eggs; mix well. Gently stir in the rhubarb. Turn the mixture into the pastry-lined pie plate.
For streusel: In a small bowl, combine 1/2 cup flour and 1/4 cup sugar. Using a pastry blender or your fingers, cut or rub in butter until mixture resembles coarse crumbs. Sprinkle over the pie.
Cover edge of pie with foil to prevent overbrowning. Bake for 20 minutes. Remove foil. Bake about 20 minutes more or until topping is golden.