it might be a good idea to find out exactly what the money will be used for. if it will be to help the needy hindus or something like that, it would probably be ok to give money. the fact that it’s run by ovdei avoda zara doesn’t necessarily mean it’s assur to give to them.
Also you might consider giving to a charity of your choice in his name and he should know about it. that would be a Kiddush Hashem.