1. Pros & cons of selecting Marathi:
If you will be staying in Maharashtra for long time, then let the child learn Marathi. As it is just beginning your child can pick up any language easily. Moreover for teaching Marathi there will be many tuition teachers also available. The child can learn Marathi easily interacting with local people and getting it taught at school. If you will be at Maharashtra for long, learning local language is a necessity and may be mandatory later for many things. You may get the benefit of that.
Cons; Marathi , in Maharashtra will be having tougher syllabus, as it is the local language. So when the child goes higher and higher it may need a good support, as the language is not talked in home. As per many students, it is tough to score high marks in Marathi in comparison to French.
Pros & Cons of selecting French:
Learning French will have a very bonus use when the student goes for higher studies or employment abroad later. There are good facilities to learn French in college levels and specialisation. Learning French canhep in getting some extra job opportunities. In schools and colleges as per students and parents French is a 'scoring subject'. That can help the student get higher chances in higher education etc. Moreover linguistic minorities(non-Marathi mother tongue) are allowed by Maharashtra state to choose a non-Marathi language. If the parents are liable to be transferred then taking French is better because Marathi may not be useful in new pace.
However not all school have regular and well qualified teachers. It will be difficult to get tuition teachers also. Alliance Francoise doe not have facilities for teaching small children. Moreover the child will have extra burden as it will not get to hear the language at home or in the neighbourhood. So it may find it difficult to proceed.
So my suggestion is, if you are going to be only for a short term stay in Maharashtra let the child take French. If you are going to stay long term, opt for Marathi.