can not quit safari. quit option is not available

Then force quit (option+command+Esc and select Safari in the pop-up dialog, or right-click on the Safari icon in the Dock, press the option key, and select Force Quit from that menu.

Download and run Malwarebytes for Mac to sweep for any malware that may be impacting Safari. Also, avoid the website you visited that caused Safari to hang.

To avoid Safari reloading its prior saved application state, press the shift key when launching it again. Clear all of your history, and if the Developer menu is present, press option+command+e to clear your browser cache. If the Developer menu is not present, then Safari Preferences : Advanced : √ Show Develop menu in menu bar. Then perform option+command+e.

If you had installed a Safari extension before it hung on you, then I recommend either disabling the extension, or removing it via the Safari Preferences : Extensions panel.

Now quit Safari from its application menu, and relaunch normally. Does it hang?