QR.3000 per month is fine for a very basic living for a bachelor.
For QR.2000,it's very hard to get an independent and decent housing in Doha. But it's possible to get a good room in places like Wakra, which is far ( about 15-20 km ) from Doha. So, if you are married and wish to bring your family along, you need to think about this housing option.

If you are a bachelor and planning to share a room with one or more people, take the option of geting QR.2000 from your company, instead of getting the housing. Because, in this case, you can find a shared accommodation for about QR.300 - 700 per month.

If you cook your food at home most of the time your entire expense may not go above QR.1000 per month.

Most important, if you are married, you cannot bring your family here for the offered salary. I suppose, the government has recently raised the minimum salary of QR.7000 to QR.10000 to be eligible to bring the family down here.