Am I able to have my mom buried with my father who is buried in a VA cemetery?

According to the website for the cemetery:
The spouse, widow or widower, minor child and, at the discretion of the Secretary of the Army, unmarried adult child of any of the persons listed above.

Persons listed above referred to the military statuses that are allowed there. So I believe you need to petition the secretary of the army for approval, but it is possible.

Angel

Your best bet is to contact the cemetery office and see what are their rules regarding spouses being buried in the same cemetery.