Hi Anna-Lilsa,
For French I would recommend Alliance Francaise centre(http://bombay.afindia.org/contact-us/) in SantaCruz (About 5 stations from Malad) Should take 30-45 mins to commute depending on traffic. Still If you are lookign for centres nearby yuo may try on Urbanclap(https://www.urbanclap.com/mumbai-french-classes-malad-west)
For dance classes again you should be able to find many options in Malad to Andheri patch.You may try looking on urbanclap or justdial.com
All the best
Saif