After marriage, if my mother-in-law runs into our room and rummages things without permission, is this infringement?

what can I say? This is a matter of upbringing. Legally speaking, of course, it is an invasion of privacy. But after all, she is your mother-in-law. If the war is not good, it will destroy your marital relationship. Be patient. If your husband doesn't point it out first, don't say it first, or it will be bad for you.