BCS class of nifedipine
The tl;dr answer is that, as the question is worded (and without an actual copy of the question or the data provided to you), its not possible to definitively assign a BCS class. 



Nifedipine is a class II drug: 


  class II is low solubility and high permeability. Formulation typically is used to enhance solubility of compounds in this class.


The data in your question is a little confusing, but you state that the compound is 'practically insoluble' which means that it must be either class II or class IV (practically insoluble definitely suggests low solubility). 

With the information provided (i.e. nothing about permeability), you cannot distinguish between II and IV. Permeability, whilst often correlated to solubility, is not directly linked, such that you cannot attempt (as I think you have tried) to calculate one based on the other (how permeable something is depends upon structure, and whether it can get through the membrane).