Going through this at the moment with my dad. Had mouth and throat cancer 15 years ago and after a couple of major operations and radiotherapy appeared to beat it. Then my mum was diagnosed with lung cancer - lung removed - but unfortunatley - and lost her battle 12 years ago. Earlier this year my dad was again diagnosed with cancer - lung - not related to his previous cancer. He has been in hospital and pallative care for the last 6 weeks - close to my home - but wanted to go his home which is about 250km from mine.
What I have done for him is give him his wish - he went home last Friday - I would have preferred him to be where I could go and visit daily - now I can only do it on weekends - I have put into place all the help I can get him to make his last weeks comfortable.
How do you cope - stay strong, look after yourself (it can be not only physically exhausting but also mentally), remain hopefull and give whatever support you can to your mum. My thoughts are with you, I know what you're going through.