We will need complement of input image therefore,

Step 1: Initially, take the $X_0$ as shown below. Now perform complement of Input the dilation of $X_0$ with the structuring element B. the resultant image is then intersected with the complement of the input image. This completes the first interaction.

Step 2: Now, the input to the second step is the first interaction. The process performed in step 1 is repeated in step 2.

Step 3: The same process is repeated again but the input to the third interaction is the output image of the step 2.

Step 4: The steps followed in steps 2 and 3 are repeated in step 4. The resultant image shown below

Step 5: The input to step 5 is the output of step 4. The process done in step 4 is repeated in step 5.

Step 6: The input to step 6 is the output image of step 5. The process done in step 5 is repeated in step 6.

Step 7: Now, we perform the union of the result obtained in step 7 with the original image to get the region filled is shown below.