As others have said, condolences to you and your friend. I agree with Dippy that a vague ‘ call me any time’ is not as comforting as contact from you. I do think that a text is less intrusive, and does not require a response there and then, if at all, but lets her know you’re thinking of her.
My dear friend’s daughter died suddenly almost ten years ago, and to this day we have never spoken about it, except for her saying ‘ before it happened’, or something like that. We communicated by card and ( short) letter for the first few years, as she would always reply that she wasn’t ready. We’ve now graduated to phone calls, and had met for lunch a few times pre-covid.
Everybody’s different, so you’ve really got to take your lead from her.
A sad situation.