Now the son of son B, which is the grandson wants to contest the will and fight for a share. If his father and he was never part of grandmother's will can he still contest
Firstly, the grandmother is not the only legal heir to the deceased grandfather who is reported to have died intestate.
Therefore the acquisition of entire property by the grandmother is invalid and illegal.
She was entitled to only one fifth share in the property, left behind by her deceased husband.
Hence she can bequeath only her share of property in favor of her chosen beneficiaries.
The legal heirs of the deceased son B are entitled to inherit the legitimate share of deceased B in the grandfather's property, hence the litigation if contested may not be successful.
Better arrive at an amicable settlement/solution instead of stretching the unnecessary legal battle.