Can self acquired property of grandfather go to only one son

The grand father passed away recently in Vijayawada 1 month facing ill health for nearly 4 years and mysteriously my grand mother passed away just a month later who was fit and healthy with no health problem. The had tow sons A and B. A the eldest had passed away and has a son C. On the day my grand mother final rituals as done B the second son comes out and shows a will Written in the year 2007 stating that the entire property and gold and money shall go to B. it states that the son and widow of A and grandson have taken the money from them and broken all ties with the family and hence all the money shall go to B. But the truth is no such incident took place in fact the grandson of A was staying in same house on the date in which the will was written and pursing his studies while the mother worked in Chennai. My question is can C challenge the will. Would he have any right to claim the property. B states that he has taken care of the house all these years so it belongs to him. If the claim is possible how to proceed. Another important information is the witness in the will are both the employers of B and not the friends of the grand father