That is one big question.
I’ll start off by saying that as fitness professionals we don’t prescribe diets so I really don’t have an answer for that portion of your question.
However, regarding the rest of your question, you state that:
1. Your client is in average health.
Are you saying that she is in average health for a 50-year-old woman? If that is the case, how do you define “average health” for women of that age group? Personally, I know some women over 50 who are more conditioned that women much younger than themselves. In a nutshell, the program you design for your client will be dependent upon the results you get from the fitness assessments you use to determine her current level of conditioning.
I wish I could give you more clarity, however, your question is a bit unclear.