Relations Between Union and States
Articles 249 and 250 don't stop a State Legislature from still making laws it's otherwise empowered to make - but if a state law conflicts with a Parliament law made under those articles, the Parliament law prevails, and the state law is inoperative to that extent for as long as the Parliament law remains in effect.
Even when Parliament exercises its temporary national-interest or Emergency powers over a State List subject, the state itself isn't barred from also legislating on that same subject - but if the two conflict, the Parliament law wins, with the state law simply set aside (not permanently voided) for as long as that conflict exists.
If Parliament passes a temporary law under Article 249 on a State List subject, and a state then passes its own conflicting law on the same subject, the state's law becomes inoperative to the extent of the conflict - but would resume having effect once the Parliament law's authority lapses.