From the facts stated by you, there are two distinct issues: (i) the legality of the construction and change of land use, and (ii) the nuisance allegedly caused by the activities of the temple and hostel. The fact that the property belongs to a religious organisation does not place it beyond the scrutiny of municipal or planning laws. If the building has been constructed in violation of the sanctioned building plan, Floor Space Index (FSI) norms, zoning regulations, or without valid permission for change of land use, such approvals can be challenged before the competent authorities and, if necessary, before the jurisdictional High Court.
As regards the obstruction of light and ventilation, while a neighbour does not have an absolute right to uninterrupted sunlight, if the construction violates the applicable building regulations or mandatory setback requirements, you may seek appropriate relief. Similarly, the use of loudspeakers is regulated by the Noise Pollution (Regulation and Control) Rules, 2000, and no institution, including a religious one, is exempt from complying with the prescribed noise limits and obtaining necessary permissions.
Before initiating litigation, it would be advisable to obtain copies of the sanctioned building plans, building use (BU) permission, change of land use approvals, and occupancy certificate under the Right to Information Act or from the Anand Municipal Corporation. These documents will help determine whether the construction and its present use are lawful. If violations are found, a detailed representation may first be submitted to the Municipal Corporation, the Town Planning Authority, and the Gujarat Pollution Control Board (in relation to noise). In the event of inaction, you may consider filing a writ petition or appropriate civil proceedings seeking enforcement of the statutory provisions.
Since you have indicated that other residents are reluctant to come forward, you may still pursue the matter individually if your legal rights are directly affected. A case supported by documentary evidence of planning violations, photographs, noise recordings, and copies of official permissions is generally more effective than allegations of corruption without supporting material.