You are doing a sterling job ...with, it would seem, little help from your siblings ! In the case of my husband, all the care of his mother fell to his widowed sister who had three children, all grown up. He used to send money to his sister and his mum for little luxuries ..and we visited from Spain once a year ...and he paid for his sister to bring his mother over every year for a holiday, when he took her out and about ..she loved the island, and so we suggested she might come and live with us (we had enough room) but she chose to stay in her flat in London, as she said she would miss looking at everyone in the street, and watching the children playing (a busy South London street) .....my husband was her favourite, but sadly when she died suddenly, he was in hospital having a knee replacement, so unable to go to London for the funeral. His daughter was staying with us at the time so I went to London for the funeral. I stayed in a hotel as one of his other sisters came over from Canada, and his other sister and his brother were also staying ....when I went to see them, to ask about funeral arrangements, they said they 'would let me know' ...and that she really wanted my husband to visit her in hospital before she died. They never told me when the funeral was, or where ...so I was unable to go ...I tried to phone everyone I knew to find out, but because of confidentiality no one could tell me . Result, his brother was appointed Executor of her will, and as she had just written 'my children' in her Will, they decided to exclude my husband as he never went to see her immediately before she died ! The Will has nothing to do with it, as she had nothing to leave, bless her ....but there were some precious photos of my husband meeting the Queen and various other small things he would have liked back (he had lent them to his mother as she asked for them to show her friends !) .....now, sadly, none of them speaks to him...
In my case, my dear dad turned down the offer of an ensuite room and small lounge in the big house I had in Essex, before I moved ...as he said 'she (my daughter who was only 4 then !) ...talks too much'.....so he got himself a retirement flat which was quite a way from me, and I visited him whenever I could and my brother went down from Newcastle to see him whenever he could ....he loved being on his own, although I worried about him ...fortunately, apart from emphysymia he was quite healthy and able to get about until the end, which was very quick ......he refused to see the doctor, so I called him from where I lived, and the doctor went but my dad refused to let him in !! Then he pulled the emergency cord in his flat one night, was taken to hospital, who rang me to tell me, I even managed, luckily, to speak to him ...he sounded ok but the next morning early he died .....before I was able to get to Ipswich, so I was very sad about that as I did love my dad, and still do, of course ! My mother was different ...always (my dad told me after she died at the age of 64 from breast cancer) said she never wanted me anyway !! I was on honeymoon when she died and so did not get to the funeral as no one told me until I got back !
My brother and I get on well, and as my job in the NHS only allowed me a few days off to sort things out, I did all that I could in the way of paperwork, phone calls, etc etc and then my brother took leave from his job and went down to sort out the flat. We each had the little things we wanted to remember my dad by ....and there was no argument over what he left, or to whom ....everything was split equally between us (I remember my dad saying, when he sold the family home to go into the flat ...I have put the money away for you and your brother) ....we both told him to spend it and enjoy his life !
It is unfortunate when siblings fall out, and make it difficult for you all. I wonder how they will cope with your mother when you are not there ? I hope your mother doesn't tell them you have abandoned her (which is not true, but some elderly people tend to do this to make it look worse than just going on holiday !) and I hope your siblings are able to cope whilst you are not there. If, when you return, things have gone smoothly and your mother is happy, you could ask her directly if she enjoyed seeing her other children, and if she would like to see more of them ...and if so, perhaps SHE and not you, could ask them to visit more often or do little things like shopping, house maintenance, etc ? Might have a better effect on them than you asking
Whatever happens, you are doing your best in difficult circumstance so you can be proud of that ! Enjoy your holiday ......you can ask your siblings to keep in touch if they would be willing to, or if you want them to, during your holiday ! Your husband is right in what he says ...but does he have elderly parents too ? ps sorry this is such a long diatribe !