You can frequently get a box set of Pooh Bear books - When We Were Very Young, Now We Are Six, The House at Pooh Corner and Winnie the Pooh.
Poetry - Edmund Lear (The Owl and the Pussycat, for example), TS Eliot's Old Possum's Book of Practical Cats. - the rhythm can be very soothing. Wordsworth, Gerard Manley Hopkins, Seamus Heaney's translation of Beowulf, Rumi, Wordsworth (I like Lines Written in Early Spring)
Alice's Adventures in Wonderland.
Passages from whatever Holy Book she might believe in - the Hitchhiker's Guide to the Galaxy if not (did that for my brother).
The Wind in the Willows. Swallows and Amazons.
If she was a teacher, she might like Miss Read Books.
If she's so unwell, she's drifting in and out, the rhythms and imagery of nature and poetry might be more like the relaxing feeling of being read bedtime stories by parents - and they can be much easier to sustain reading for a long stretch.