I know a sister whose husband passed away on Saturday. She has to go back to work to pay for the bills. What are the things that she has to do to follow the Shariah?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

There is no harm for this woman who is in her waiting period after the death of her husband to go out to work in order to pay her bills, if there is nobody who would fulfill this for her.

Imam Muslim reported in his Sahih that Jabir (Radiya Allahu Anhum) said: "My maternal aunt was divorced, and wanted to pick dates from the date trees so one man prevented her from going out (to pick the dates as she was in her waiting period).  So she came to the Prophet (Sallallahu Alaihi wa Sallam), and the Prophet (Sallallahu Alaihi wa Sallam) said to her: "Of course, pick your dates.  You may give some of them in charity or spend them in good (field)."

Allah knows best.