Suggesting someone take responsibility for themselves and begin to experience gratitude and generosity accordingly is not exemplifying "bah humbug". Quite the contrary.
Most people who are ungiving never are happy, don't regard what they have as being adequate to meet their needs and judge others negatively for not giving enough to them.
There's this expression, "an attitude of gratitude." When you're grateful for your life, that you are housed (much less a "new home"!), that you even have children who are alive and with you...a thirty minute walk seems like nothing!
Get a dratted bicycle. Call a neighbor. Attend a church and ask for some sort of network helps for basic transportation. Sign up for ride-share, save for a one-time taxi ride home...there's so much this woman could do, I mean, make her own decorations and enjoy herself and her children and laugh and sing and love one another! That's a Christmas many people with illustrious things never experience.
This woman's plight is so minor, it's pitiful that she's feeling down and without. Just pitiful. Not that she lacks things but that she lacks gratitude and character.
Someone in her neighborhood could and should help, yes, for the Holiday but I fear that unless this woman gets some other intervention, she will always be complaining about not having a ride, being too isolated, nothing, no one, not enough...
I know nothing about this woman and I don't assume to know. Not everyone is resourceful and good at problem solving. It just seems like it may be problem with a fairly easy solution. I made a suggestion instead of an immediate reaction to poo-poo her situation.
btw - My immediate reaction to her Christmas tree dilemma, was that she should buy a small fake tree, it's light and easy to carry.