it will only go up. She bought at $4200

How soon can we REALISTICALLY see $4200 again and upwards?
Not advisable to put all her money on a bitcoin. You should just put at least %10 of it. Because, it's huge money, anytime it may drop down big time. You need to manage things by just putting a small portion of income. Always take note that, the money on bitcoin is always not guaranteed. It may change for the better or for the worse.