Create a view that summarize vehilce owned from two tables cars and bikes
As far as you should not provide information enough about your table schema, I've improvised this one:

create table _owner(_name text, _ssn text);
create table _cars(_ownername text, _owner_ssn text, _model text);
create table _bikes(_ownername text, _owner_ssn text, _model text);
insert into _owner values
  ('me' ,'1'),
  ('you','2');
insert into _cars values
  ('me', '1','Ferrari Modena 360'),
  ('me', '1','Porsche Macan'),
  ('you','2','peugeot 205');
insert into _bikes values
  ('me', '1','Specialized Tarmac'),
  ('me', '1','Pinarello Dogma'),
  ('you','2','Scott Silence');


You can use COUNT and GROUP BY to get your desired result:

select o._name, o._ssn, 
       ((select count(*) from _bikes where _bikes._owner_ssn = o._ssn)
       +
       (select count(*) from _cars where _cars._owner_ssn = o._ssn)) as total_cars_and_bikes
from _owner o
;


+-------+------+----------------------+
| _name | _ssn | total_cars_and_bikes |
+-------+------+----------------------+
| me    | 1    | 4                    |
+-------+------+----------------------+
| you   | 2    | 2                    |
+-------+------+----------------------+


Check it here: http://rextester.com/UZMF16252