It is always appropriate to thank people for their kindness.

What I am questioning is whether the daughter has the emotional energy to do something that might very well be poison in a wound, remembering a time of hope when she's now lost that hope. And 'it is not appropriate now' is less about what is appropriate socially and more about what is appropriate for her.

In which case, mum, you're not listening to your daughter. LISTEN BETTER.