Capital gain

I have a problem in computation of capital gain.
Land has been purchased in the year 1990 for 56,000. In the year 1991 he constructed ground floor Rs.3,00,000
In the year 2007 he constructed 1st floor Rs.6,00,000
In the year 2015 he demolished the building.
In current year he is going to sale the property for 2,60,00,000
1.What value I have to consider as on 01.04.2001?(land+building) or (only land)
2.can I claim cost of improvement?
3.Now he is going to purchase a residential house for 1,10,00,000 can I claim this amount as a deduction u/s 54.
In the previous years we shown the land and building as an asset in the income tax returns.
Please tell me sir what I have to do?