There are lots of free webinars out there...I just listened to an Amy Porterfield's session on "Facebook likes." She promoted a "list building" webinar from Nathalie Lussier...got good information from both.
Does a 65 year old woman who hasn't worked out in years need muscle confusion? Thinking sometime simpler may help client achieve goals, which I'm assuming would be a safe consistent fitness routine that she can maintain into her next decade. Good luck.
Consider a simple journal to record daily food intake - it's one of the top tools people who have lost weight and kept it off use - level of detail can be geared to individual. Some people will benefit from becoming mindful of what they put into their mouths, other may be able to zero in on eating ...
There are lots of independent Zumba instructors that teach outside of traditional gyms such as community centers, schools, dance studios - try a google search. If, by chance, you are in NJ - I can refer you to some awesome instructors.