Explanation

She has been supporting her family since her husband’s death.

وہ اپنے شوہر کی موت کے بعد سے اپنے خاندان کی کفالت کر رہی ہے۔

Since is used to refer to the starting point of an action or situation that continues into the present.

She has been doing it from the time her husband died — and is still doing it.