name    number      date
a       1.2         123.2
b       123.2       3/13/2019
c       2.3         3/14/2019
d       569         3/15/2019
e       abc         3/15/2019
f       30          abc
g       39.8        -3
h       3/21/2019   3/19/2019
i       -395        3/20/2019
j       4           3/21/2019

name    number      date
a       1.2
b       123.2       3/13/2019
c       2.3         3/14/2019
d       569         3/15/2019
e                   3/15/2019
f       30
g       39.8
h                   3/19/2019
i       -395        3/20/2019
j       4           3/21/2019

df['date']=df['date'].apply(lambda x: None if str(type(x))=="<class 'str'>" else x)

df['date']=df['date'].apply(lambda x: x.strftime('%m/%d/%Y')if not pd.isnull(x) else '')

df['date'] = pd.to_datetime(df['date'], errors='coerce')

df['number'] = df['number'].apply(lambda x: None if str(type(x))=="<class 'str'>" else x)