I'm a CALS (caregiver/friend of ALS patient) - my friend was also fairlyl recently diagnoised (Aug.) with bulbar onset. At first, I didn't know what to do either but I am close to the family and I have witnessed their reactions over the last few months. What I can tell you is that it has been very hurtful to them when people have avoided the topic or ignored his illness. If you can imagine, even their PASTOR has dropped the ball on this one (promised to call, visit and never has). Some family members (although admittedly not close) have ignored it, also very hurtful.
This family was/is devestated and to ignor their grief has been more hurtful than to bumble through a few words of compassion or an awkward visit. They have most appreciated cards/ notes (although at first they were hard to read and some were left unopened for a few weeks- then slowly they were all read and have been kept). Some have sent food (also apprecaited). Some sent practical gifts (filing boxes to help sort through all the incoming doctor bills, ALS information, legal stuff) - appreciated.
One thing I sent them recently was a very small dry ease board - I think it was a difficult gift to receive (because it was a reminder of how he is loosing his ability to speak) , but it was used almost immediately (he has trouble speaking for long periods and sometimes can't finish a thought. With the board, he can continue his conversation).
Bottom line, it is important not to remain silent. Show up, take something, send notes, check on him, offer to help with appointments, shopping, etc.....