E.S.
Did you ask the parents what the child's sleep schedule is like on the weekends? I found that it helps if the schedule at day care is the same as at home on the weekends.
I agreee, a one hour nap doesn't seem like enough sleep for a 9-month old... heck, my little guy is 18 months and still takes a morning and afternoon nap (and sleeps through the night). Although we actually like to spend time with our child in the evening, so he stays up until 9pm with us. :)
Good luck!
E.