Why does your alternator and speed sensor fuse keeps blowing on a Honda Civic LX?

you probably have a short in the fuse box, check the fuses and check it again, if it's not that check the wiring from the sensor and the alternator. any of them may need replacing.
You have a short circuit under the intake manifold where the wire harness crosses over the intake support bracket. Raise the car, go under and look up on the back side of the motor - look up under the intake manifold. There is a steel support bracket and a large wire harness just above it. the wires have rubbed on the bracket and worn through their insulation. Lift the wires back and tape everything up. It isn't even expensive to fix!!!