The following CSS entries in UserChrome.css file will do the following to Firefox context menu (right click options):
Remove Send Link to Device
#context_sendTabToDevice, #context_sendTabToDevice_separator {display: none !important;}
#context-sendpagetodevice, #context-sep-sendpagetodevice {display: none !important;}
#contentAreaContextMenu #context-sendlinktodevice,
#contentAreaContextMenu #context-sep-sendlinktodevice {display: none !important;}
Remove Open Link In New Window
#context-openlinkinusercontext-menu {display: none !important;}
#context-openlink {display: none !important;}
Remove Bookmark This Link
#context-bookmarklink {display:none !important;}