My Huz & I are both cancer survivors. Doom & gloom come along with cancer diagnosis. Fear sets in instantly as soon as the doc says you have the big C. Not all will survive the treatments & those who do have ongoing thoughts of cancer returning, especially with those darn yearly tests.
I'd suggest sending a nice note thanking her for the treasured items. Tell her you will pray for her recovery & let her know if there's anything you can do to please contact you. Let her know you're willing to talk/listen if she's willing. If possible send her a nice lap quilt or fleece blanket. She'll be glad to have it during treatment.