If you are thinking about some small business, how about Flea Market, Farmer's Market, which are seasonal and weekends. Get Nepali handicrafts and be able to sell them might be another options. But if you if are planning to keep your parents here for a long time, then social interaction skills is a must, whether they like it or not, which all depends on how much educated they are back home and their willing to change. So volunteering is the "only" best way to learn, not through books, internet, or TV.
Day care is out of your league, it is very complicated, period.
If you're in a descent size city, there will be a lots of program for minority and immigrants which you can get all the info from the city office. There will be free ESL and lots of other activities for FREE. Use the best of the green card, free American public services. If you dig deep, there are many. Remember, your parents have as much rights as a citizen to rip those benefits.God bless America.