بسم الله الرحمن الرحيم
When you visit your native place i.e. Dhanbad though only for one day or four days, you will offer full salah and do not offer qasr salah there. After you leave Dhanbad you will become musafir. Yes, if you stay in any place for fifteen days then you will become musafir and will offer four rakahs and if you stay there less than fifteen days then you will remain musafir and offer salah with qasr.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.