I think it would be a nice gesture to take something to eat.
I've had so many people in my family pass away and believe me, the food is really appreciated because no one feels like cooking, no one feels like going to a restaurant. It's nice to have some things on hand that were lovingly prepared. One person might feel hungry and need something to eat while another might only be able to manage a few bites of things here and there. It's really hard to think of something that even sounds good to eat so something someone else brings might look really delicious.
A casserole is nice, a potato or macaroni salad, even a veggie or deli tray with some bread for them to make sandwiches....In my experience, food is always appreciated. I wasn't usually able to eat much, but the kids got hungry and it was so nice not to have to worry about cooking anything for them.
Since she's still there, I wouldn't go over just yet. Even though you didn't feel close to her husband, I'm sure he's very, very aware that you offered your friendship and sent her cards.
I think it would be okay to call and say, "This is Amy. I'm so sorry to hear of her passing. She was a wonderful person. I was hoping you could let me know when might be a good time to drop over either later tonight or tomorrow to offer my condolences."
That way, you might be able to kind of get a feel for the situation and an idea of what they're comfortable with and where they are with their arrangements for a service etc. By saying "maybe later tonight", it implies you understand that before then wouldn't be comfortable for anyone, including yourself.
People who have lost a loved one are very understanding and very appreciative of expressed sentiments. Take your cues from the family.
I'm very sorry you lost your friend.