一个外国朋友的妈妈去世了,去参加她的葬礼应该对他家人说点什么?

Normally, you don't have to say a lot when meeting with the family after the funeral, if you don't know the person, you can just "I am really sorry." If you had met the person before, you can also say something nice about her.

Just make sure that you wear something proper to the funeral, such as a black dress or something more reserved.

You can also bring a nice condolence card to him when you go to the funeral. Also, you can say to him that "if there is anything I can do for you, please don't hesitate. You can always call me if you want to talk."