Its been three months that I haf a muscle strain and its still weak. Is sugery an option?

No. Not sure which muscle you have ' strained' but surgery for a muscle 'strain' is not an option.., it will slowly get better w/ time. If you have avulsed(pulled off the bone) a muscle or muscle- tendon attachment ( such as the pec major tendon or biceps tendon ; the elbow) then surgery us the best option... But for 'routine ' muscle strains in the 'belly' of muscle avoid re- injury and give it time!