LISTEN! That is always appreciated.
Thinking of you cards, maybe flowers. Something to let her know she's loved and important to you. One of my best friends did that after I'd sounded really down about a week after the ex left. It was a big help to look at those flowers and know that someone really cared enough to spend money on them (yes, that was an issue for me!).
Try to get her out of the house for dinner, lunch, movie, play, etc. If she's like many women, we move out of our parents home to be with our spouse and are unaccustomed to living alone.
At first, the lack of a companion to talk with (the dog didn't respond to any questions, lol) was hard-so the phone calls to check in are good, too.
Suzanne