pandas - ???

import pandas as pd
from io import StringIO


def unnest(df, col, col2,reset_index=False):

   col_flat = pd.DataFrame([[i, x]
                      for i, y in df[col].apply(list).iteritems()
                          for x in y ], columns=['I', col]
                           )

   print(col_flat)
   col_flat = col_flat.set_index('I')
   df = df.drop(col, 1)
   df = df.merge(col_flat, left_index=True, right_index=True)

   if reset_index:
       df = df.reset_index(drop=True)

   merchant_product_code = (df['Product code'] + '-' + df[col])
   df['item_group_id'] = df['Product code']
   df['Product code'] = merchant_product_code

   return df


text = '''Product code,Options
COWZGH,"['Newborn (2.5-6kg)', 'Big Baby (6-9kg)']"
PHBC,[]
ORGWBT0,"['Newborn (2.5-6kg)', 'Big Baby (6-9kg)', 'Preemie (1.5-2.5kg)']"
COVWDBC,"['Newborn (2.5-6kg)', 'Big Baby (6-9kg)']"
COVWMV,"['Newborn (2.5-6kg)', 'Big Baby (6-9kg)']"
BZ-168,[]
ORWNG,"['Newborn (2.5-6kg)', 'Big Baby (6-9kg)']"
ORWNB13,"['Newborn (2.5-6kg)', 'Big Baby (6-9kg)']"
HBCDTG,[]'''

# read data from text
fd = StringIO(text)
df = pd.read_csv(fd)

# convert strings to list

# version A - create empty lists []
#df['Options'] = df['Options'].apply(eval)

# version B - create lists with empty string ['']
df['Options'] = df['Options'].apply(lambda x: eval(x) if eval(x) else [''] )

# print type for every row
df['Options'].apply(lambda x:print(type(x), x))

df2 = unnest(df, 'Options', 'x')

print(df2)