Oracle 18c

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create table table1 (Name varchar(100), Customer varchar(100), Location varchar(100));

insert into table1 
    select 'Jane','BEC','Texas' from dual union all
    select 'Jane','BEC','Texas' from dual union all
    select 'Jane','ARC','California' from dual union all
    select 'Jane','BEC','California' from dual 

4 rows affected

select t.Name,  t.Customer, t.Location,
      (select t2.location 
       from table1 t2
       where t2.name = t.name
       group by name, location
       order by count(*) desc
       fetch first 1 row only
      ) as most_frequent_location
from table1 t 


NAME
CUSTOMER
LOCATION
MOST_FREQUENT_LOCATION


Jane
BEC
Texas
Texas

Jane
BEC
Texas
Texas

Jane
ARC
California
Texas

Jane
BEC
California
Texas


select t.Name,  t.Customer, t.Location,
       max(location) keep (dense_rank first order by location_count desc) over (partition by name) most_frequent_location
from (select t.*,
             count(*) over (partition by name, customer, location) as location_count
      from table1 t 
     ) t


NAME
CUSTOMER
LOCATION
MOST_FREQUENT_LOCATION


Jane
ARC
California
Texas

Jane
BEC
California
Texas

Jane
BEC
Texas
Texas

Jane
BEC
Texas
Texas

NAME	CUSTOMER	LOCATION	MOST_FREQUENT_LOCATION
Jane	BEC	Texas	Texas
Jane	BEC	Texas	Texas
Jane	ARC	California	Texas
Jane	BEC	California	Texas