Coworker's grandfather passed. Wake is hour away. Just met coworker this year. Will a card suffice?

Just a card will suffice. If it was a circumstance where you knew the coworker for a long time, or even had a friendship or acquaintance with the deceased person than it would be a better idea to give something along the line of money or some kind of gift. But since you just knew the people for a little while than a card will suffice and it will not be breaking any kind of typical societal norms to give them more.