**Core Concept**
Postpartum blues is a common condition affecting new mothers, characterized by a group of symptoms including mood swings, anxiety, and emotional instability. It typically occurs within the first two weeks postpartum and is thought to be related to hormonal changes, particularly the rapid decline of estrogen and progesterone levels.

**Why the Correct Answer is Right**
The symptoms described in the question, such as crying, loss of appetite, difficulty sleeping, and low self-esteem, are classic features of postpartum blues. This condition is often triggered by the sudden drop in estrogen and progesterone levels after childbirth, which can lead to feelings of sadness, anxiety, and emotional instability. These hormonal changes can also affect neurotransmitter levels, such as serotonin and dopamine, contributing to the development of postpartum blues.

**Why Each Wrong Option is Incorrect**
**Option A:** Postpartum psychosis is a more severe condition that typically occurs later in the postpartum period, often within the first few days to weeks. It is characterized by severe depression, hallucinations, and disconnection from reality, which are not present in this case.

**Option B:** Postpartum depression is a more chronic condition that can occur anytime during the postpartum period. While it shares some similar symptoms with postpartum blues, it is typically more severe and persistent, often requiring medical treatment.

**Option C:** Postpartum anxiety is a condition characterized by excessive worry, fear, and anxiety about oneself or one's baby. While it can occur in conjunction with postpartum blues, it is not the best term to describe the symptoms presented in this case.

**Clinical Pearl / High-Yield Fact**
Postpartum blues can be managed with supportive care, including counseling, social support, and reassurance. It is essential for healthcare providers to recognize the symptoms of postpartum blues and differentiate them from more severe conditions like postpartum depression and psychosis.

**Correct Answer: C. Postpartum blues**