What times do the 3 last 872 buses leave from Nanxin Village to Deshengmen in Beijing?

It is hard to tell the exact timing, but the bus stop service at 19:00 and the operational frequency is 10min. It takes 15min or so from Changling to Nanxin Village. So you may see the last bus around 19:15. Then calculate the timing of the last two.
Anyway, the approximate time is just for your reference.