Kharijah bin Zayd (may Allah have mercy on him) said: When the grandmother from the mother's side is nearer than the one from the father's side, she has the greater right to the sixth; and when the grandmother from the father's side is nearer than the one from the mother's side, the two of them will share in the sixth.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الفرائض / 12366