How much is the Class Imbalance Problem rates? I'm working on a data set and wanted to know is there a standard rate about Class Imbalance problem or not?

I have 47 samples in Class A and 150 Sample in class B , should I use Class Imbalance Technique or these rates are normal?
There is no general rule but you better to use such techniques (SMOTE, sampling etc) and try to obtain 50:50 if you can. 
You can utilize my another answer (just ignore multiclass part).

My suggestion is you should create more samples by synthetic data generators like SMOTE. You have a model with very less observations (197). The model may not fit well thus data generation may help your for that case.

Hope it helps!