Allow is a verb which uses both an object and an infinitive.
The object is the person/entity who gets the permission.
Examples:
i) The boss allowed you…
ii) The law doesn’t allow anyone…..
iii) I haven’t allowed anyone…..
To infinitive after the verb allow denotes what can be done as a result of that permission:
Examples:
i) ……allowed to file taxes after due date.
ii) ….allow anyone to break the law.
iii) allowed to take a retest.
Thus, we will say allow someone (allow to someone will be wrong).
Let’s take a look at full sentence examples:
i) No one is allowed to take law in his hands.
ii) The principal allowed Sunil to take the exam from home.
iii) How can you allow your juniors to use official car for personal purposes?