I think I have found the answer to my question. The total number of shares is around 2.86 crores as per the latest Shareholding Pattern (checked on both BSE and NSE). The market cap should be around Rs 90.6 (CMP) x 2.86 crores, that is, around Rs 260 crores, which is same as the market cap shown on Screener.in.
The market cap shown on BSE website is much higher—around Rs 650 crores. I was able to solve this mystery too. There is a huge ongoing rights issue. It will add 4.3cr new shares, making the total to around 7.16cr shares. The market cap on BSE reflects the contribution from the new shares too.
[Earlier I remarked about “free-float” market cap. Free-float is irrelevant here. I learnt later that free-float refers to the non-promoter portion of the market cap (“freely” trading).]
The company notified a couple of days back that it has “committed” investments of around Rs 230 cr. It is unclear if this Rs 230 cr is already reflected in the balance sheet or some of this amount will come from the rights issue. As per the latest balance sheet, the company has around Rs 150 cr of assets (after subtracting liabilities). Given this information, there appears to be quite a lot of margin of safety. The rights issue will give a huge war chest to the company and increase the promoter holding from around 35% to above 50%.