In a small bowl, mix topping ingredients with a fork until crumbly.
Heat oven to 350 degrees. Lightly grease and flour the bottom and sides of an 8 1/2-by-4 1/2-inch loaf pan.
In a large bowl, stir together flour, sugar, baking powder and salt. In a separate medium bowl, whisk evaporated milk, oil, lemon zest and eggs until combined. Pour egg mixture into flour mixture; stir to combine.
Pour batter into prepared pan. Sprinkle evenly with crumb topping. Bake 1 hour to 1 hour and 10 minutes until a toothpick inserted in the center comes out clean. Cool bread in pan 10 minutes, then carefully remove from pan. Transfer to a cooling rack to cool completely.
In a small bowl, combine ingredients for the glaze. Drizzle evenly over fully cooled bread.