Reimbursement of *reasonable* costs of alternative arrangements would indeed be due, AIUI (as long as evidence is kept in the form of unused train tickets, taxi receipts etc.), but that still requires the passenger to be able to front the cost of alternative transport in the first place.
If people are physically unable to make these arrangements for themselves because insufficient taxis are available, I’m not sure what the railway can be expected to. It cannot magic buses and taxis out of nowhere at the drop of a hat, late on a Friday evening, to accommodate potentially thousands of stranded passengers.