it will only go up. She bought at $4200
How soon can we REALISTICALLY see $4200 again and upwards?
Oh god, just because some people told you to do so, you wen't and suggested your grandma to put all her lifesaving's in bitcoin. That's just heights of stupidness. Be glad that the price has increased right now and not crashed, or else she would have had a heart attack of some sort.
It might be all good right now, but what if you are away and she needs the money badly? You are better off taking the profits you have and giving it back to her now, or else risk it. Its all upon you.