• Preheat the oven to 375°F. 
• Lightly grease and flour a 5 by 9-inch loaf pan and set aside. 
• In a medium mixing bowl, cream the margarine and sugar together until it becomes light and creamy.
• Add the eggs and milk, and mix well. In a small mixing bowl, sift together the flour, salt and baking soda.
• Add this to the margarine-milk mixture, and   stir until all ingredients are thoroughly combined.
• Stir in the vanilla and hot rhubarb and mix until well combined. Pour the batter into the prepared pan. 

Topping

• In a small mixing bowl, combine the margarine, flour, water, sugar, and cinnamon. Use a pastry blender to mix the ingredients thoroughly.
• Pour the mixture over the bread batter.
• Bake for 1 hour, or until a toothpick inserted in the center comes out clean. Let cool 10 minutes in the loaf pan, and place the loaf on a wire rack. Slice, and eat either warm or cool.