My mom asked my husband what?!?!?

Okay, so the other day my husband and I were sitting on the couch watching tv. My mom is visiting from Cali and we live in Michigan. Anywho, as my husband and I start to get ready to go to our sons doctors appointment my mom asked my husband a question that I personally felt was none of her buisness and disrespectful honestly...."When do you get paid?!" My husband looked at me with a "do i really have to answer that look" then answered her to be respectful of course. Meanwhile, I was legit in shock that she would even ask him that. Like no one comes to your house asking your husband when he gets paid! So what makes you think its ok to come to my house questioning my husband?. ..like I honestly felt like she was over stepping boundaries. Then she goeson to basically say that we are paying for the family to go to an outing.....like are you going to ask or are you TELLING US? We do have bills & kids....amongst other things. This is OUR household and you don't just ask personal questions like that... I mean maybe im tripping... I didn't say anything to my mom because she has this thing where she takes eveything personal. My big question is how do I tell her she overstepped without starting drama? Or am I overreacting?! Either way I need advice ladies!!! WWYD?

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Update:

1. ifeel she was asking to much because my mom has stolen money & used me before. We don't have the best relationship.

2. Overstepping boundaries was her volunteering us to pay for a group of people to go out...WITHOUT ASKING US FIRST(that is why she was asking)