In a bowl, combine 1/2 cup brown sugar, cinnamon and salt. Add squash, pie filling and lemon juice. Pour into a greased 9-in. square baking dish. Cover and bake at 350 degrees for 30 minutes.
In a small bowl, combine the flour, oats and remaining brown sugar. Cut in butter until mixture resembles coarse crumbs. Sprinkle over squash mixture. Bake 45-50 minutes longer or until topping is golden brown and squash is tender.