Hopefully, the Finance Bill, 2017 will become an Act and the proposed amendment to reduce the holding period from 3 years to 2 years for a long term asset will be applicable with effect from the assessment year 2018-19. Assuming that this amendment takes place, the capital gain on sale of your house in Bangalore in April 2017 will be Long Term Capital Gains (LTCG).
The purchase cost of your house is Rs 35 Lakhs, as mentioned by you, in the financial year 2014-15 will be adjusted for cost inflation index, which is yet to be prescribed for the FY 2017-18. The index prevailing in the FY 2014-15 is 1024, while it is 1125 in the FY 2016-17, which is just about 10% over the two years. Assuming that the index will be about 1180 for the FY 2017-18, your adjusted cost of acquisition will be Rs 40.33 Lakhs, i.e., 35*1180/1024. The exact amount will depend upon the cost of inflation index, which is yet to be prescribed for the FY 2017-18.
The LTCG will be around Rs. 60 Lakhs. You may claim exemption of this amount, if you invest the LTCG of Rs 60 L in the purchase of another residential property u/s 54 or in the capital gains bonds u/s 54EC upto a maximum of Rs 50 Lakhs.
The registration expenses incurred by you for the purchase of the property are also part of your cost of acquisition.
The improvements to your house actually incurred by you can be added to the cost of your house being sold and indexed for the purpose of arriving at LTCG.
There is no need to submit the bills for the cost of improvement, while filing your return, but you need to preserve them and submit in case you are asked for. The cost of improvement is an issue of fact, which can be supported with documentary evidences like bills and /or corroborated with other evidences like valuation report and photographs of improvements done.