Will my grandma survive a 2nd hip replacement? what are the statistics?

Likely: The success rate depends upon the age of grandma, the cause of the need for the first replacement, the reason for the failure of the first replacement, grandmas level of activity and compliance and her overall health. Orthopedic surgeons like good results, and are not likely to operate upon someone unless they expect good results. Ask the orthopod about expectations.

Many factors: There are too many factors to consider before giving you a number for your grandma, e.g. How old is she, does she have diabetes, does she have heart disease? But there is some reassurance that hip replacement is a good idea (when indicated) and leads to longer survival, see: http://goo.Gl/xeziq.