Long term capital gains

I came across a case. A person inherited a residential house from her father through a will (will was dated Dec 1965). 

In 2016, she sold the property. From the sale consideration, half of the amount was invested in a new residential house (new house is registered in her son's name). Balance amount, they have kept in fixed deposits. Now, the queries are:

1. Cost to previous owner not known - So what is the way forward;

2. Can the new house registered in son's name qualify for deduction.

Thanks

Pavan