Buses will be operational depending on the State you live in, but will not operate in any containment zones.
Movement of buses and vehicles between states can only happen if your State agrees with another State to open borders and start transportation services of the State(s)/ UT(s) involved.
Within your State
Movement of passenger vehicles and buses within a state will be as per the guidelines given by the State. For example, the Kerala government has allowed buses to operate in a few zones.