money from sell of property as gift??

for ebay (72 Points)

14 June 2018  
suppose Mr A is a super senior citizen and has sold his property for 24 lakhs.

He has a brother-B,
son-S,
daughter-D and
sons wife(daughter in law of A)-DL

now can "A" give this 24 lakhs to. B, D, S, DL (4 lakhs each that is 16 lakhs)

q1.....can B, D, S, DL spend thus money in anyway they like...or they need to invest this money in property only.

q2.....is gift deed is also necessary


q3....also how to calculate capital gains...if cost of property is unknown (property bought in 1920s)