To calculate the total amount Britney will spend and how much change she should receive, we first need to find the total cost of the shirt and the hat.
- Cost of the shirt: $30.79
- Cost of the hat: $19.75
Now, we add the cost of the shirt and the hat together:
\[ 30.79 + 19.75 = 50.54 \]
Next, we subtract the total cost from the amount Britney gave to the clerk ($100.00):
\[ 100.00 - 50.54 = 49.46 \]
Therefore, the change Britney should receive is $49.46.
The correct answer is B. $49.46.