I would suggest asking what help your friend would like.  I have found that sometimes people put their own needs to help above what the person themselves wants so I'm always conscious of this .  It could be that staying away and giving the person space is in itself very helpful.  I suppose it depends on the person and what their personal circumstances are.  Practical help is useful eg baking a pudding , doing the weekly shop, having the children over for a play date etc.  Or it might be a case of sending an occasional text with an uplifting anrcdote about what's been going on in your life.  Id take the lead from them.  If you ask how they are and they say ok and change the subject that indicates they don't want to talk about it further.  But if they start to talk you can follow that path as well. Hope that helps and look after yourself too.