I've travelled back from work in London to Hull hundreds of times in the last 10 years and, fortunately, I have only ever needed to abandon my journey once (that was due to heat causing problems). Luckily I had somewhere to go that evening and travelled back the following day. If I ever get in that situation again I have two questions:-
1. If there's a total closure of Kings X is the best route back to Hull to go St Pancras EMR to Sheffield, then any service to Doncaster and then on to Hull (or direct Sheffield to Doncaster if available)
2. Presumably if that isn't possible due to, say, problems at St Panc then it's a matter of hanging around until LNER (or whoever) sort out alternative arrangements.