Am I overreacting about my MIL coming into our house when no one is home?

My in-laws have the passcode to our house. While my husband and I were on our honeymoon, they came into our house and took a table that belonged to them without telling us. Since then, there have been a few situations where my MIL asks my husband for something, he tells her it’s in our garage, and they come into the house and get it themselves.
Recently, I checked our security footage and saw them going through items in our garage and taking a storage rack because they thought it was garbage. They never asked if they could take it.
I told my husband that I wasn’t comfortable with this and asked him to talk to them. I wanted him to explain that they shouldn’t be coming into our home when we’re not there and shouldn’t be taking things without asking first. His mom became very upset and told him to check our money and gold to make sure nothing was missing because apparently now they’re being treated like thieves.
Now my husband is angry with me. He says his mom comes first, that it’s wrong for me to tell his parents they can’t come into our house, and that they’re welcome anytime, whether we’re home or not. He also says they can stay at our house even if we leave.
Am I wrong for expecting people even family to ask before entering our home and taking things? Or is this a reasonable boundary to have?