How to find the minimum value among the columns in Python

I have a DataFrame as below. Based on few conditions I need to retrieve the column

Wifi_User1      Wifi_User2      Wifi_User3    Thermostat    Thermo_Pos     Act_User1      Act_User2    Act_User3    Be_1   Be_2   Be_3
  -58             -48             -60             18             -50             0               1           0        1       1      3
  -67             -45             -60             18             -50             1               0           0        1       2      3
  -40             -65             -65             18             -50             1               0           1        3       2      3
  -67             -45             -44             18             -50             0               0           1        2       3      4
  -65             -68             -70             18             -50             0               0           0        1       3      2
  -55             -60             -65             24             -50             0               0           0        1       3      2
  -72             -56             -45             24             -50             0               1           0        2       1      1
  -75             -45             -60             24             -50             1               1           0        3       1      1
  -77             -48             -65             24             -50             1               1           0        1       1      2
  -70             -58             -68             24             -50             1               0           0        2       2      3
  -70             -75             -65             24             -50             0               0           0        2       2      3
  -55             -45             -65             24             -50             0               0           0        2       1      4
  -65             -55             -70             15             -50             0               0           0        2       1      4
  -65             -55             -70             15             -50             0               1           0        2       1      1
  -55             -45             -65             15             -50             0               1           0        1       1      4
  -67             -45             -44             15             -50             1               0           0        2       1      4
  -65             -68             -70             15             -50             1               0           0        2       1      1
  -67             -45             -44             15             -50             1               0           0        2       1      4

The condition is :

 if (Wifi_User1!=Wifi_User2) or (Wifi_User2!=Wifi_User3)
 or (Wifi_User3!=Wifi_User1) or (Wifi_User1!=Wifi_User2!=Wifi_User3) 
 and when the thermostat value is changing

Then take, the difference between Wifi_user1 & Thermo_Pos, and same goes for 2 and 3. Take the minimum among these difference, and return 1 in if its Wifi_User1, 2 if its Wifi_User2 and 3 if its Wifi_User3 in the new column say, "User".