is there an earphone for ipod that works with hearing aids?

Etymotic Research, Westone Laboratories and many Hearing Practices also offer custom iPod® molds, earpieces, in-ear-canal headphones.

There is also a second generation iPod Touch application SoundAMP. It was called an "interactive hearing device", but is not really a solution for people with hearing loss 

Sounds like his hearing aids dont have Bluetooth built in.   Not to worry. There is a solution. 

In case you dont know, Bluetooth is the wireless connectivity that the IPod and most new cellphones have built in.  

 All hearing aids sold in the US in the last 10 or 12 years have a T-coil (telecoil)  built-in.  This allows the hearing aid to recieve a (electromagnetic induction) signal from any  telecoil, and in this case, its a "T-coil to Bluetooth"  adapter.  There are various adapters out there, but the least complicated and expensive would be a bluetooth to T-coil "neckloop" like this

I tried one out, cost about $115.  Works great except I am getting ready to replace my aids and the next set I get must have bluetooth built in.  On the other hand, I do not listen to music with hearing aids, as aids never reproduce music with any kind of fidelity.  Nothing like wearing a good set of headphones with the music turned up to comfortable listeining level.  

Good luck Hope this helps