Final answer:
The correct grammar structure to fill in the blanks is 'Voy a la casa de mis abuelos.'
Step-by-step explanation:
The correct grammar structure to fill in the blanks is 'Voy a la casa de mis abuelos.' In this case, 'voy' is the conjugation of the verb 'ir' in the first person singular, 'a' is the preposition indicating movement or direction, and 'la casa de mis abuelos' is the location being referred to.
Learn more about Grammar structure for expressing movement and location in Spanish