Unfortunately, your situation is in a grey area that there is no right or wrong.
A grace period is not compulsory under the law, but a matter of mutual consent. In this case, what you can do (and not do) depends on your agreement with the landlord.
Since there is no agreement between the landlord and the tenant for the grace period, it becomes a he says, she says situation.
Reasonable or not, it depends on the perspective of the landlord and the tenant respectively.
There is no solution in this case unless either or both sides compromise.