In a bowl, combine the first five ingredients. In another bowl, combine the eggs, pumpkin and oil; stir into dry ingredients just until moistened. Fold in apples. Fill paper-lined muffin cups two-thirds full. In a small bowl, combine sugar, flour and cinnamon. Cut in butter until crumbly. Sprinkle over batter.
Bake at 350 degrees for 35-40 minutes or until golden brown. Cool for 5 minutes before removing from pans to wire racks.