Now my question...what can she realistically expect from this weapon?
The short answer is that, while a very lucky shot from a .25 may
eventually be fatal, a more typical experience in the short term is multiple rounds expended on the target with no effect on the attacker's actions in a short enough time frame to be of comfort to the victim.
Attackers are stopped by:
1) Psychological shock (they think they're hurt badly so they shut themselves down - not common)
2) Destruction of a critical component of the musculoskeletal support structure (e.g., the pelvis) - won't happen with a .25
3) Destruction of a critical component of the central nervous system (brain or spine) - would require VERY lucky shot with a .25, e.g. through an eye socket
4) Loss of oxygenation to the brain from either the destruction of the circulatory system or massive hemorrhage due to damage to major organs (heart) or blood vessels (aorta, pulmonary artery, etc.)
Even large caliber bullets give widely varying results, and there are no "magic" handgun rounds that deliver a one shot stop all the time. The rule of thumb is that bigger bullets carry more energy, penetrate deeper, and create larger wound channels than smaller bullets. As would be expected, they deliver proportionately better results.
An example occurred in my neighborhood when I lived in Florida. A BG forcibly entered a single woman's home at 06:30 and attacker her in her bedroom. She reached her .25 auto and emptied it into him. He proceeded to severely beat her until he lost consciousness from his wounds. The victim was beaten so badly, when she went to a neighbor's door for help he didn't recognize her and refused to let her inside.
While the victim in this case survived because the damage she was able to inflict with her .25 was sufficient to disable her attacker before he finished killing her, the damage she suffered was severe. If an outcome similar to this is acceptable to you, the .25 may meet your requirements. Otherwise, make the additional investment in time, effort, and money to go with a .38 or larger caliber.
A similar topic was discussed at some length in another thread under "Anyone else CCW a Mousegun?" Before you make a final purchasing decision, you may want to review it at:
http://www.texasshooting.com/TexasCHL_F ... =7&t=16349