Emma D asked:
My mother is travelling from Munich to Salzburg in November and I would like to arrange for a car to pick her up at Munich airport and drive her to Salzburg. Can anyone recommend a good chauffeur/taxi company in Munich that would do this?

You could try this:
Your mother could get a taxi to the main railway station (Hauptbahnhof) and from there get the fast train to Salzburg, and then a local taxi to where she wants to go. The fast train takes 1 hour to reach Salzburg from Munich.