Serum creatinine level reduced from 6.9 to 6.7 within 3 days and again reduced from 6.7 to 5.5 within 4 days. diaysis is required or not ?

Dialysis: its impossible to tell whether you need dialysis based on 3 creatinine readings. It looks like you're going in the right direction, but I have no idea of the circumstances which caused you to end up there. A high creatinine is concerning, and yours is very high. But, if it's all from an acute injury or infection, then you're less likely to need dialysis than if it's from diabetes, for example.

Difficult to say: It is a difficult question to answer based on the limited information provided. The cause, duration of renal failure, comorbid conditions etc all play a part in the decision. Your nephrologist would provide the best guidance.