Also, I don't care much what anyone else says or any books. If you can afford paying for your grandma and its no major trouble to you, you should do so as a good deed before she dies.
On Judgment day, you can blame me for it, and say I told you to do it. I'm happy to take the credit for an elderly person's hajj, and you should be too! Jump at the opportunity to do good if you're able and it doesn't cause destruction to yourself.
If you are Muslim, you follow the rules of the Shariah. Khalaas.