Tuberculous Meningitis: The combination of headache, neck stiffness, low-grade fever for one month, and CSF analysis showing turbid appearance, low glucose, high protein, and a lymphocytic predominance (neut: 27, lymph: 87) is highly suggestive of tuberculous meningitis. The chronic nature of the symptoms and the specific CSF findings point towards this diagnosis.

Bacterial Meningitis: Although the lymphocytic predominance in the CSF is more typical of viral or tuberculous meningitis, some cases of bacterial meningitis can present with a mix of neutrophils and lymphocytes, especially in the early stages or with certain pathogens. The turbid CSF and low glucose support this possibility.
Viral Meningitis: This condition can present with similar symptoms, including headache, neck stiffness, and fever. However, the CSF glucose levels are usually normal, and the protein levels may not be as high as in tuberculous meningitis. The lymphocytic predominance in the CSF is consistent with viral meningitis.
Fungal Meningitis: This diagnosis should be considered, especially in immunocompromised patients. The symptoms and CSF findings can be similar to those of tuberculous meningitis, with low glucose and high protein levels.

Subarachnoid Hemorrhage: Although the CSF analysis does not directly suggest hemorrhage (e.g., no mention of blood or xanthochromia), this condition can present with sudden headache and neck stiffness. It's crucial to consider and rule out due to its high morbidity and mortality.
Meningitis due to Less Common Pathogens (e.g., Brucella, Leptospira): These pathogens can cause meningitis with similar symptoms and CSF findings. They are important to consider, especially if the patient has been exposed to animals or has a history of travel to endemic areas.

Sarcoidosis: Neurosarcoidosis can present with meningitis, among other neurological manifestations. The diagnosis is often suggested by a combination of clinical findings, imaging studies, and histological evidence of non-caseating granulomas.
Carcinomatous Meningitis: This condition involves the spread of cancer to the meninges and can present with symptoms similar to infectious meningitis. It is a rare diagnosis but should be considered in patients with a known history of cancer.
Granulomatous Meningitis due to Other Causes (e.g., Histoplasmosis, Coccidioidomycosis): These fungal infections can cause granulomatous meningitis, especially in endemic areas or in immunocompromised patients. They are rare but important to consider due to their specific treatment requirements.