Hi Walid
Welcome to Madagascar and congratulation for the job.
I'm Harison.
Do not worry about the cost of life . It's the one of cheapest in earth.
Remember that minimum salary is 50 € in Madagascar .
But Cost of life is roughly about 100 € - 120 € if you live like an average Malagasy people.
But if you live like an "Expat" , then expect to pay about 400 € for living Without the rent . And house rent in big cities is about 300 to 400 €.
Madagascar is less dangerous than South Africa for example .
But the main issue is the "small" robbery ,like pickpocket or sometimes a steal of your belonging when you are in public transport .
We do not have any terrorism issue as well and we deeply respect all religions . Killing is rare . Just do not show any "wealth" sign such as big watch or jewels.
I would say you will be safer in big cities .
Poverty is very tuff in madagascar so be ready to get culturally shocked ( you will see homeless children, elderly , women and starving people)
Again , welcome to Madagascar.