Hi Lisa,
These days there’s really no job security no matter where you work. You can get laid off from anywhere at any time. So with that in mind, you really should go where you feel you’ll be challenged the most, and where you’ll enjoy being, and where you will have the most chance for growth and advancement.
Husband and wife companies often have their own set of challenges, because you’ll always be the “3rd wheel” in the company. If business slows down they may need to make a choice on who they keep employed and who they let go. Who do you think makes the cut in that situation?
If the “mom and pop” shop would faint at $50K, perhaps they are not the right fit for you. If their quality is unsurpassed, they should be charging the rates that woud support your salary. Good luck.