To Accompany
する verb
The same accompany means you are in the same place as someone, and you are accompanying them. This word means to accompany. This is only used for accompanying people.
どうはんする
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
今日は奥さんが同伴するのかと思ってたよ。
I thought you would be accompanied by your wife today.