One-time pad encryption of ASCII characters
So you were really close. You are right that the 3rd ciphertext's 10th byte(0xED) in the 3rd message is a space. So we know 0x20 in hex is a space in ASCII. So now to find the 10th byte of the key you need to xor 0xED and 0x20 to get 0xCD(which is the 10th byte of the key). Well now that you know the key, you can xor the 10th byte of the 3rd ciphertext 0xBD with 0xCD. So you get 0x70 in hex and 'p' in ASCII.