"I wonder f you know her husband?" - incorrect.
"I wonder if you know her husband?" - correct. Both 'wonder' and 'know' are in the present tense. This sentence is usually used when you are talking to someone, and this thought suddenly comes to you. Here is an example:
A: Hi B! How are you? What are you doing these days?"
B: Hi A! I'm great! I'm working at the supermarket downtown.
A: Oh really? I wonder if you know C? She works there too.
B: Yes, I know C. What a small world!
"I wondered if you know her husband?" - technically incorrect. 'Wondered' refers to a time in the past when you thought about something. The second part of the sentence, 'know her husband,' refers to the present time - you know someone currently. But, in English, the verbs must agree in tense. So, native speakers might say this sentence, but it is better to say "I wondered if you knew her husband" or "I was wondering if you knew her husband."
"Do you know....?" is direct.
"I wonder if you know...." is more indirect.
"I wondered if you knew..." or "I was wondering if you knew..." is even more indirect.