Birthday of friend's son

I (25M) am suicidal but have found comfort in a friendship with an older guy I've been chatting to at the pub. He told me (without knowledge of my attempts) that his son who was the same age as me, killed himself 2 years ago. It was very sobering to hear that from him. This Friday is his sons birthday and his family his having a celebration at the pub we drink at together. I'd like to do something nice for him as hes become a bit of a father figure for me. I was going to drop off a card or some flowers, is this inappropriate? Or what other things could I consider doing like maybe putting some money on a tab?