Capital gain tax on parent gift property?

Since your dad gifted you the property, it was exempt at that time. Hence the cost of acquisition of property for you will be 1 lac. However, since it is before 1st April 2001, the cost to be considered will be Fair market value as on 1st April 2001 or 1lac whichever is higher.
This FMV will be need to be done as per a valuation report by a CA/valuer.

The calculation of capital gains will be as follows:
1. Sale price = 5 crores.
2. Less: Cost of acquisition as above * 331/100
(The 331/100 is the cost inflation factor as notified by income tax department for FY 2022-23)
3. Less: Cost of improvement. i.e. 2 crore * cost inflation index for the year when the improvement was done.

The resulting figure will be the capital gain which will be taxed at 20% since it will be long term capital gain.

This is the rough calculation. It is advisable to consult a practising CA to guide you/ do the calculations as it requires expertise.

Here cost to the previous owner is pertinent. Generally on inheritance there is no tax. But tax on appreciation on capital gain