Closed loop plant-control system
Your solution is correct but an easier method (I think) is to use superposition, first we will suppress r ( i.e. we will ignore r ), then get the transfer function, then suppress d then get the other transfer function, then sum the two up to get the final transfer function.

When we suppress r will then get 

$$
\frac{Y}{d} = \frac{P}{1 + PC}
$$

and when we suppress d we will get
$$
  \frac{V}{r} = \frac{C}{1 + PC}
$$

but Y = VP meaning

$$
 \frac{Y}{r} = \frac{PC}{1 + PC}
$$

We the sum up the two values of Y to get the final response of

$$
  Y = \frac{P}{1 + PC}d + \frac{PC}{1 + PC}r
$$

There is no transfer function from d to y because y depends on both d and r, you can't evaluate the value y without knowing both d and r values.