Birthday idea

It's not really a "must" I guess? But if you want to, look into functional and practical things - most people would avoid snacks/food items. Generally, don't give others what you wouldn't want to receive - maybe practical items like wet bags, small colouring sets etc? You can also check with the centre because they usually have general guidelines as well, and remember that the cake (if you're getting one) usually has to be halal certified! Meaning, no home bakers, no bakeries with certification :)