Hi, Gram!
It’s important that you take time to visit beloved family members who have already passed the pearly gates. It’s the least you can do to show that you still love them for everything they’ve done for you. This person was offering a passing “Hi, gram!” to her grandmother while driving past her cemetery.
The next day, someone said that they saw the OP driving past the cemetery with someone sitting right beside her. Based on the description, that person looked exactly like the OP’s grandmother, the very one whom she greeted that night! We’re not huge believers of the supernatural, but even this one gave us the creeps.