I don't see any reason why not. If the grandson was under the age of 19 on Dec 31 of the tax year and the *GRANDSON* did *NOT* provide *MORE* than 50% of *HIS OWN* support during the tax year, then if the other requirements are met (lived with you, etc) it's not an issue.
To help you out next year, will the grandson be attending college upon graduation from high school?