In the below dataframe, is it possible to find the Date at which maximum occured by groups

```
df
Date        Var    Value
27/9/2019    A       56
28/9/2019    A       50
1/10/2019    B       90
2/10/2019    B       100

df1      Max         Date          Mean
A        56        27/9/2019        53
B        100       2/10/2019        95

```