Adder-Subtractor Circuit
The first sum is correct, the carry C is just the but that comes from the sum of the most significant bits, in this case 1.

The overflow is straightforward to calculate once you know the values of C3 and C4 (C).

The second sum is wrong, probably because you didn't sum the carry in (M). The least significant bit of the sum becomes 1+1+1=1, then you can work it out from there.

Try these pointers, if you have further doubts add them to the question.