Like stated in the above posts, the circumstances ares different. Some have medical costs, some have house to pay off, some might be living in rented places, some may have car/bike loan. If there are no loan or any installments and other recurring expenses, in my PERSONAL opinion around $300 a month should be enough. Again, this is for parents only and for expense like grocery and other everyday expenses. Besides this, pareko bela ma aru ta chadai chha like medical/surgery expenses, dashain/tihar/chad baad and other irregular expenses.

I agree that easy money will made habits worse and even if you send $5000 per month, that will not be enough. Manchhe ko baani nai kharab.