I understand her reaction. In Nigerian culture, we dont say i love you to each other in a family, we show our love for eachother through our actions. We could love eachother to the point of being willing to give your life for your patents or siblings but never ever say i love you, we just know it in our hearts and try to show it.
I have a grandma that is just like this, tsundere but loves you so much through actions, and i also have a grandma that's just sweet and happy all round. God bless for my grandmas for taking care of me all these years