The migrants workers should have been provided with required amenities and a proper shelter within the states they were working in.

Three points:
1.This lockdown will be lifted at some point & they'll need work at that point. And their home states where they had moved from certainly can't accommodate their labour which is why they migrated in the first place.

2. It'd have saved them a miserable journey back home. It'd have saved the humiliation. And it'd have helped containing their chances of getting infected too.

3. Plainly speaking, there's a central government to blame. But the state governments should be held doubly responsible, especially those of Maharashtra and Delhi are to be blamed for the treatment of the workers that had helped building their states for so many years.

If they'd ensured a proper accomodation and curbed the panic, this crisis wouldn't have happened at all. Unpopular opinion: No one should be advocating their migration back home. Their migration back home is a huge problem in itself. Question the accountability of the states.

See this thread for the problems they'll be facing after their migration back home: https://twitter.com/Albert_Camuk/status/1262129602962567172?s=19