* Lola - This is the most common word for grandmother, and it refers to both your mother's and your father's mother.
* Lolo - This word refers to your grandfather, but it can be used to address both grandmothers and grandfathers respectfully.
For more specific terms:
* Lola sa tuhod (grandmother on the mother's side)
* Lola sa ama (grandmother on the father's side)
It's always helpful to know the context to choose the most appropriate word.