What do I say in response to my boss's bereavement?

I hoping that some Etiquette Jellies out there can help me.
I was trying to schedule a meeting with my boss, and in an email he said that he wouldn’t be available for the next week because he must prepare for his mother’s memorial service.
Should I express my condolences in a response email, or would that be tacky? I am inclined to send a card, but there still remains the fact that I have to respond to his email somehow, and that is where I am stuck.