First of all you should understand the difference between the registered title document and the revenue records.
The registered partition deed confers title to the allottee to the share of property being allotted to him/her.
The village revenue records are not the title records, hence anyone claiming title by the village revenue records is not legally maintainable.
Further when the court has passed a decree and judgment on the basis of compromise arrived between B and C allotting separate possession of their respective share in the property, they both become absolute owners of their respective share in the property.
What is your doubt about the title to B in the property?
The legal position is that since B being the absolute owner of the share of property allotted to him, he can dispose his share of proeprty to anyone of his choice in any manner hat he may desire and decide. His authority over such disposal cannot be challenged or questioned by anyone for any reason, and any such challenge would be defeated as they are not legally tenable or maintainable.
As I opined earlier, why do you have to pursue this matter when you are not absolutely sure of the title to the property especially when the local advocate have opined differently or have hesitated to recommend the purchase.
However, if this is the only defective part in the documents what you observe, in my opinion, it is ignorable and one can proceed with the purchase.