To find the unit rate of muffins per cup of almonds, we can divide the total number of muffins by the total cups of almonds used.
Manny made 36 muffins and used 4 cups of almonds.
The calculation is as follows:
\[ \text{Muffins per cup of almonds} = \frac{\text{Number of muffins}}{\text{Number of cups of almonds}} = \frac{36 , \text{muffins}}{4 , \text{cups}} = 9 , \text{muffins per cup of almonds} \]
Thus, the unit rate is 9 muffins per cup of almonds, which corresponds to option B.