All perfect praise be to the Lord of The Worlds, and may his blessings and peace be upon our Prophet Mohammad and upon all his family and companions.
The guardian of a virgin bride is her present father, and it isn`t permissible for her grandfather to act as her guardian while her father, who is Muslim, mature and of sound mind, is present because he is closer to her in kinship and Asabah{Male blood relatives from the father`s side}. "The bride`s Asabah himself is her guardian"{Hashiat Ibn Abdeen, 311-312, Vol.2}.
The Jordanian Civil Status Law No.(36), (2010), Article (10) stated: "The guardian of a bride is her Asabah according to the order included in the preponderant opinion of the Hanafi school of thought." In addition, article (16) stated: "When one guardian approves to marry off the bride to a certain suitor, the objection of other guardians becomes void"
In conclusion, the grandfather isn`t allowed to act as the guardian of his granddaughter so long as her father is competent to be her guardian(mature and of sound mind), and he isn`t allowed to object to his son`s marrying off his granddaughter. However, we advise the bride`s father to make reconciliation with his father in order to bury any grudges. And Allah knows best.