Yes, Axis is definitely right about carrying on asking.
A card would be better than flowers, and a letter even better, as it is something which can stay with someone who's bereaved, no matter what time of day or night s/he needs to hear words of comfort again, and know that someone has taken time over a letter.
You mentioned being in different countries: are the time zones very different? If so, you could mention this to your friends, as there will be times when they literally can't get anyone else on the telephone to talk to, and yet feel desperately lonely....
Do be prepared, though, for them not to want to see you. I have a friend who lost her baby last year, and she can't bring herself to be around babies, much less the baby of another, mutual friend, who was born on the due date of the one who died. This is hard for the friend whose child lived, especially as there's nothing she can do; it's just something she is, nothing she did. That's not what you want to hear, of course, but is worth bearing in mind. 