U/s 54 assessee gets exemption if he purchases any residential house 1 year before or 2 year after or if he construct a house within 3 years from the date of transfer. But it is nowhere specified that on whose land the the construction is to be done or whether or not cost of land will be included in the cost of construction or not.
And 1 more thing If the land is purchased 6 months before the date of sale of 2 years before the sale will the exemption b available in any of the case.