Preheat oven to 450°F Grease a deep 1 1/2 quart baking dish.
TO PREPARE FRUIT: make a syrup by boiling the sUgar with water until all sugar is dissolved. Remove from heat and cool. Add vanilla, rhubarb and strawberries. Pour into baking dish.Bake until filling is hot and bubbling around the edges, about 25-30 minutes.
FOR DUMPLINGS: Sift flour with sugar, baking powder and salt. Cut in butter until fine; add milk and stir just enough to blend.
Remove Fruit filling from oven; drop dumpling mixture by spoonfuls over fruit mixture.
FOR TOPPING: Blend brown sugar with soft butter and sprinkle on top of each dumpling.
Bake in prepared oven for 15-18 minutes or until dumplings are a nice golden color.