Ansible: How force kill process and exit from ansible-playbook if not successful?

I have two bellow tasks as part from my playbook

      - name: "Verify httpd.service no running on node {{ ansible_hostname }}"
        shell: "ps -ef | grep httpd"
        register: _ps_httpd
        become: true
      - name: stop httpd is exit code eq to 0
        shell: "kill -9 $(ps -ef | grep httpd| awk '{print $2}')"
        when: _ps_httpd.rc == 0
        become: true
        ignore_errors: true

This two tasks that should force kill process. Currently I'm getting the error

"msg": "non-zero return code", "rc": -9

What do I miss here? Any idea how to get resolve this?

In addition, I would like to add the option exit from ansible-playbook run if not successful.

To achieve the goal in Ansible it is recommended in general to use service modules, service, sysvinit or systemd. In example like

---
- hosts: localhost
  become: yes
  become_method: sudo

  gather_facts: yes

  tasks:

  - name: Gathering Service Facts
    service_facts:

  - name: Make sure service is stopped
    systemd:
      name: httpd
      state: stopped
      enabled: no
    when: ("httpd.service" in services)

If you like to use the shell_module, for me more work was necessary.

In example for nginx get the right PID first, since there are a primary and four worker processes.

- name: Get nginx PID
  shell:
    cmd: "ps -C nginx -o pid --no-headers | head 1"
    warn: false
  changed_when: false
  check_mode: false
  register: nginx_pid

It would also be possible to do something like

- name: Get nginx PIDs
  shell:
    cmd: "pidof nginx"
    warn: false
  changed_when: false
  check_mode: false
  register: nginx_pids

- name: Show PIDs
  debug: 
    var: nginx_pids

- name: Kill nginx
  shell:
    cmd: "kill -9 {{ nginx_pids }}"
  ...

Regarding

I would like to add the option exit from ansible-playbook run if not successful.

to end the playbook run you could use

- meta: end_play
  when: condition_is_met

use fail_module to

- name: Task has failed because of
  fail:
    msg: "{{ fail_message }}"
  when: condition_is_met

or the assert_module.

Regarding the exit code (EC) or return code (RC) you may have a look into How do I get the list of exit codes (and/or return codes) and meaning for a command/utility?.