Saur, as FvM has said, your op-amp cannot go to either rail. The output cannot reach down to 0V if the negative supply is GND. You either need to supply the op-amp properly with + and - voltages, or use an op-amp designed for single supply operation.
The offset null will not help you. It is to account for the
input offset voltage; it certainly cannot change the output swing. If you check the datasheet, you will see that the maximum range for the offset null is about 4mV anyway, so how do you expect it to account for 1.5V?
To try to help you understand
why the op-amp cannot swing all the way to the negative rail, take a look at the schematic on page 2 of this datasheet:
https://www.ti.com/lit/ds/symlink/op07c.pdf
You will see that the output (pin 6) is connected to the supply rails through a number of transistors. Each transistor has a V
BE drop, moving the maximum output swing away from the relevant supply voltage. This applies to both power rails, so by running the op-amp at +5V/0V, you are limiting the output to a few volts in the middle of that 5V range.