Hi
i am so sorry for your colleagues loss - when we lost Thomas we did not want to talk to anyone for a while, particularly at work. I felt like a complete failure to go back to work without the baby or the bump. The best thing you can do is let your colleague express their feelings to you rather than you to them.

A card and flowers are extremely thoughtful and that is all that is required at this stage. Your colleague will let you know when they are ready to talk.

You will probably never know what really happened to them and that is their decision - i returned to work and asked everyone to treat me as though nothing had happened and they did. That helped me and I am sure your colleague will tell you what will help them.

Hope that helps, sorry i rambled.
tess.