بسم الله الرحمن الرحيم
In the above mentioned case if your friend gave all his property to his second wife in her complete possession and withdrew his ownership from it then the second wife became the owner of all the property. The son of the divorced wife shall get no share in it.
In case the deceased only registered the property in her name and did not make her its sole owner or did not give it into her complete possession then the second wife will not become the owner of the property. And thus all the property of the deceased person became his inheritance and it shall be divided among all his Shariah heirs according to their Shariah shares and the son of the divorced wife shall also get his share in it.
Allah knows Best!
Darul Uloom Deoband