The Replacement by Melinda Di Lorenzo

Ari Strange thought she'd survived the worst after the sudden death of her husband. She couldn't have been more mistaken...
Nearly two years have passed since Ari's husband died in a shocking hit-and-run, and she's finally beginning to feel normal. She has a job. An apartment. She's fully focused on her miracle-her 13-month-old daughter, Lucy-Kate. And she never dreamed it could all go sideways again in an instant...
On a freezing winter night, Ari wakes to find a blood-covered woman taking Lucy-Kate from her crib. In minutes, she goes from frantic parent to being accused of kidnapping her own daughter. The police don't believe her story. They don't even believe that Ari is Ari. Rather, they've taken the side of the woman who claims-with proof-to be her. The only person who gives Ari the benefit of the doubt is her unfriendly neighbor. But his behavior is sketchy, his motives unclear.
As evidence mounts against Ari, the time to save Lucy-Kate is running out. Can she uncover the truth before she loses everything all over again?