Combine peaches, blueberries, flour, sugar, cinnamon, lemon peel and vanilla in a large mixing bowl. Gently stir to combine. Place mixture in unbaked pie crust.
For crumb topping, combine flour, sugar and nutmeg. Cut in butter until mixture resembles coarse crumbs. Sprinkle topping evenly over pie. Place pie on a baking sheet. Bake for 50 to 55 minutes. Serve warm or chilled. Top with ice cream or whipped cream, if desired.