It seems like you don't have enough information. Being a single mom who has made bad choices but is working to keep her daughter safe doesn't sound like someone who ends up getting targeted by Child Services unless there is more backstory. That doesn't mean she has done anything wrong - an angry ex could be reporting possible abuse, for example.
Has she asked for more than just sympathy? Would you be comfortable acting as a character witness (active member of church group, observed positive interaction with child, child appears happy and healthy, etc) without claiming to know her outside of that one setting?
I agree with Joe Mama. It sounds like you're looking for a good and kind thing to do for this person, but need to see what the boundaries are and need a little more backstory. Honestly, you can probably be a huge support to this person just by being willing to hear her story and not communicating judgment to her, and not shunning her. That's more than most people are able/willing to do in these situations.