240 lbs for a 5 ft 4 in person is still a very high body mass index of 41.2.   According to the National Institute of Health, that is quite obese.  A BMI of over 30 is defined to be Obese.   She would have to get down to 174 lbs to no longer be considered obese, and become classified as being badly overweight.

At 340 lbs, she was at risk of suffering very early disability and even death.  She has indeed made great improvement.  But this amount of progress will only delay her getting heart disease, type 2 diabetes, and all of the other serious maladies associated with obesity.   She might be able to get through her 40's in relatively good heath, but by the time she reaches her 50's, it will catch up with her.

She really needs to get down to at the very least 160 lbs, if she wants to have any quality of life when she is older.   Let's hope that this trip allows her to do just that.

You can calculate your BMI here:

http://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm