I have no idea how much it costs, and there are various brands on the market. It is an injection generically known as the 'mistmate jab'. Your vet will know what is best to give the bitch.

The bitch was probably frightened, hence the getting frantic. Dogs can be raped just like humans can.

It is very responsible of your friend not to allow her ot have pups, she is far too young. Maybe you coudl suggest to him that in future he either doesn't take his bitch out when she is in season, or perhaps has her spayed? The mismate jab can increase the future risk of pyometra, so spaying is probably best anyway.