If it's any help, I perform a lot for my granny too. She loves anything and everything visual ! I can name some tricks I performed to her and she loved them..
1) Two Card Transpo - You can learn this by performing a double lift- a standard card sleight taught in most beginner's card books. Royal Road to Card Magic would be sufficient !
2) Ambitious Card Routine - This amazing routine is available, believe it or not, free of cost. I'm not posting the link here (unsure about rules). Just go to lybrary.com , click on 'Free ebooks and articles' on the left, and download the Card College 2 sample. (However, I felt uneasy after using it for free and immediately bought it. You could if you wanted to
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3) Card Warp
There are lot's more. Design for Laughter comes to mind (available in the book mentioned in point #1. Damn my memory !!
