Beginner - unable to use AND gate with buzzer and flashing light circuit
If you want the transistor to power the 555 oscillator circuit then the transistor should be an emitter-follower. Then one switch can be between the emitter and the positive supply of the 555 circuit and the other switch can be between the base of the transistor and +9V.
Connect the collector of the transistor to +9V.

What is the photoresistor for? So that the circuit works in darkness or in sunlight?