it is difficult when family members get older, i'm experiencing this with grandparents and their siblings.
the last remaining are in late 80's and 90's and have had health, mental and physical, issues become more apparent over the last couple of years. He is 98 and was still living on his own (with a cleaner and weekly visits by us) up until early last year. sadly he has alzheimers and now is back in the 1950's when he had his own business and sometimes you see him sat as if he is assembling or sewing something. he does have good days when he recognises us and bad when he has no idea who he is let alone us. We are lucky that he is in a lovely care facility and within 10 mins of us instead of over an hour away. i know that he is going to join his late wife soon though, and sadly for my father as (it is his uncle) it'll be farewell to the last of his mother's family of that generation.
his personality can have days when he's not who he would consider as himself, and that's the nature of the illness sadly.
she has taken to her bed, not ill just decided to not get up. and that breaks my heart as she is (i know i shouldn't have one but she is!) my favourite grandparent. she spoilt us with love and home baking. hugs and trips out, not needing to buy us things, we are the only grandchildren on that side of the family and the attention was the best thing. i'm almost too sad to see her at the moment as i'm dealing with health issues and am not sure i could keep it under control long enough to visit.
sorry i got a bit rambly there, what i meant to say is don't feel guilty Thipu, parents and grandparents get older and we can only do so much for them and as you had only just gotten back from a long trip i do think she was a little OTT in her demand that you must be there for thanksgiving. would it soften her if you sent her some pictures from your trip? maybe in an album book (online printers? photobox in uk, not sure US)