A property was purchased on the names of wife and son, thus title to the property is already there and very clear so intestate death will not arise. A Will may not cover the property bought under Benami transactions until and unless it is proved while probating the Will
After death of the father his property would devolve upon his legal heir including his wife.
In your query the property was purchased in the name of wife and son. Now, this property would be spare from law of succession. Father could not have disposed off the property which is not in his name by a WILL. This WILL is bad in law.