“ Now therefore, I pray you, swear to me by YHWH, since I have dealt faithfully with you, that you also will deal faithfully with my father's house, and give me a true token, and that you will save alive my father, and my mother, and my brothers, and my sisters, and all that they have, and will deliver our lives from death.”
They were to swear by their own God, for then they would take it seriously. The word ‘faithfully' is the word used for ‘covenant love', containing ideas of kindness, loyalty and faithfulness. Kindness on its own is not strong enough as a translation. It involves commitment. She considered, quite reasonably, that her actions had committed them to her so that she could count on their assistance in return. With that in view she asked for a token of that commitment, which they gave her with an oath (Joshua 2:14) and with a piece of scarlet thread which was probably itself a commitment token (Joshua 2:18).
A piece of scarlet thread seems to have been a regularly recognised token (Genesis 38:28; Genesis 38:30; Song of Solomon 4:3). Possibly it was a commitment token (sometimes a love token), worn round the neck (compare Genesis 38:18).
“That you will save alive my father, and my mother, and my brothers, and my sisters, and all that they have, and will deliver our lives from death.” They would recognise that any commitment to her involved her family. She pleaded only for close family, blood relatives and their families, that they would be given their lives and allowed to retain their possessions. As she does not mention a husband she was clearly unmarried (or widowed).