The question is whether she should pursue it, not you. Carriers will only deal with the passenger.
There are still details missing. Yes, it is unfortunate that the delay was 24 hours and yes, it is unfortunate that the hotel was full. But, what was the alternative? Was this poor service or was it simply the best that could be done under the circumstances?
Water under the bridge for you, but it really pays to make sure that when elderly relatives are traveling and you believe that they might not assert themselves for them to have a mobile phone with your #'s pre-programmed. It can be for emergencies only, but you are better equipped to deal with this and make sure that your relative gets the best that can be had under the circumstances.