There are many levels to this person's problems
If this person is a Filipino has a recording of the agency saying she needs to pay off her fees first, then she needs to go to the Phil Consulate and file a complaint for overcharging. It should be zero placement fee and only 10% of salary one time.
To quit she needs to give one months notice in writing. The she leaves after 30 days with no extra payment of salary from either side. Buy her own food now and at the final settlement give them the receipts for all food items purchased and do not sign final paperwork until they pay for the food. Take photos of spoiled food for evidence or record conversation that show maltreatment.
If they will not allow her to go out even on her off day, she can leave without notice as this breaks the terms of the contract. The reason they are so controlling is that they know it is wrong to treat her this way and are frightened to be caught out.
If they fight for her to resign with all evidence in their favor, she should tellt hem she wants to go to the agency and settle because she does not understand how this system works. DO NOT SIGN ANYTHING until she understands. This is important, because once she signs she resigns cannot change it.
To file a claim she must wait 7 days before approaching Labour Tribunal and then she writes it all out and they send the complaint to the employer with a date for a conciliation meeting.
During this period of time she cannot get another job and will need to pay for her own expenses to stay including an extension of visa for $190.
The system is rigged against a DH to make a case due to the excessive costs whilst waitng for the LD meeting. Also the Labour Dept cannot force the employer to settle with payment even if they say the DH has a good case. Employer must pay for the air ticket home and travel allowance. Any untaken annual leave earned and rest days that were worked.
Take the complaint to the country Consulate in addition to the LD so the next DH will not need to bear such hunger and controlling behavior.
Good luck