Brake padle goes on floor after change master clynder and brake boster.

Hello, The master cylinder is what needs to be bled. After bleeding the master cylinder, the brake lines must be completely flushed and bled, because you are trying to remove air from all the way at the master cylinder connections to the wheels. It will take some time, but you will eventually get a firm pedal. Especially if the master cylinder is correctly installed and bench bled.