**B. N380m**

The equilibrium level of income is the level of income at which the total amount of goods and services produced in an economy is equal to the total amount of goods and services demanded.

In this case, we are given the following equations: 

Y = C + I

C = 50 + 0.75Y

I = N45m

Substituting the second and third equations into the first equation, we get:

Y = (50 + 0.75Y) + N45m

Y - 0.75Y = N45m + 50

0.25Y = N45m + 50

Y = (N45m + 50) / 0.25

Y = N380m

Therefore, the equilibrium level of income is N380m.