Let's say financial crisis hits, 90% of P2P loans default. Will the p2p lending company be liable for anything or they are free from any responsibility or liability to investors?

The P2P company did the heavyweight lifting of checking up the companies, their repayment scheme and the possibility of the default.

But still, it's just a Facilitator for peer, to, peer lending. Hence they are not liable unless sufficient evidence is withheld (material facts) that could lead you NOT to invest in the particular deal (which is very rare based on the fact they do their due diligence).