I got myself into quite a pickle please help!?

So last week my friend got me with the scary maze prank and i thought it was really funny, so i decided to get my grandma with the scary maze prank aswell. But it turns out i scared her to much, because she had a heart attack!!!:O.She is in the hospital and i feel quite guilty. How do i make it up to her? Is it to soon to try and scare my grandpa with the maze prank too?