It sounds like this friend feels a sense of being 'incomplete'. She may be putting herself out to fill this void. She may too be feeling the need to be acknowledged or valued. Could there be an aspect in her life (maybe a relationship) where these things are missing? So too, does she have control of things in her life? It is possible something like a relationship, or job, etc, is leaving her feeling brow beaten? Sometimes the need to help people results from emptyness or a need to find something one can control in an otherwise uncontrollable life. Regardless of the reason, this individual needs to feel some value.

Instead of dealing with the issue of the reluctant volunteering to help, approach it from the angle of her being the one in need.