Is the salary and companion's allowance that I receive, by virtue of being a companion to my sick son abroad, halal or haram, even though I have not permanently accompanied him for over a year?

The ruling on the entitlement to salary and expenses depends on the condition set by the state. If the term "companion" refers to someone who accompanies the patient, then the questioner is not entitled to salary and expenses except for the days of companionship. However, if it refers to the expenses of someone generally responsible for the patient's affairs, there is no harm in receiving it to spend on those entitled to it. The questioner can consult the officials to clarify the nature of the grant. If it becomes clear that he took what he was not entitled to, he must return it.