Any chance for legal advice for mr.b?

One Mr.A a father purchased a premises on Mr. C's name that is his second son.But during the purchase he was not sure whether to put the name of Mr.C the second son or Mr.B the elder son.But since he put the name of second son Mr.C, he made sure that he gave the premises to the elder son Mr.B to  run bussiness with a power of attorney from the second son Mr.C.Today it has past over 17 years that the elder son Mr.B who is in possesion of the premises and also have licences on his name for that particular years.Now the worry is? for example.If the younger brother Mr.C ask Mr B the elder son to vacate the premises what shall be done?Cause for a 17years he have been taking care of that particular premises and also just to start business all over again somewhere else is a very difficult task.what is the best to do.if he Mr.C ask  Mr.B to vacate the premises is it good to vacate or challenge in it in the court. If he does challeneg it  will there be any help for Mr.B.cause the father is no more.