Do you know if they are new muslim or old.
it might make a difference.
Traditionally gifts are not exchanged for this event. It is an event to celebrate a sacrifice, so it is a sacrificial celebration.
It is common to celebrate by:
Wearing your best cloths (not a tux).
Giving a card
Cooking a food dish and taking it to them: cake, lamb shank (no pork or beef).
My recommendation is to ask your friend what is expected. That is perfectly ok.
A gift as you and I know it is not appropriate.