If so what was her job?

Vinnie

I'm not sure if she worked in the cartoon but she did in the movie. I think she worked for an advertising company or something like that.

That may be because the movie is of more recent vintage,the
cartoon and tv series are of course older and in them she is
a housewife.And believe me any mother who has a Dennis for
a son has a full time career just keeping him out of trouble!!!!!:)