All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
It is a good thing that a woman is blessed with a pious husband who is keen on preserving her religion and who endeavors to protect her from causes of temptation; this is an obligation on the husband. Allaah says (what means): {O you who have believed, protect yourselves and your families from a Fire whose fuel is people and stones, over which are [appointed] angels, harsh and severe; they do not disobey Allaah in what He commands them but do what they are commanded.}[Quran 66:6] Ibn Abbaas interpreted that 'protect your families' means: “Teach and discipline them.”
There is no doubt that the human being is social by nature. A man likes to have male friends, and likewise, a woman likes to have female friends; however, a friend influences his friend positively or negatively. It is for this reason that we are urged by the Sharee’ah to choose pious friends. Abu Moosa Al-Ash’ari narrated that the Prophet said: "The example of good company and bad company, is like that of the seller of musk and the blacksmith who blows bellows. The seller of musk will either give you some perfume as a present, or you will buy some from him, or you will get a good smell from him, but the one who is blowing a pair of bellows will either burn your clothes or you will get a bad smell from him." [Al-Bukhari and Muslim]
Abu Saeed Al-Khudri related that the Prophet said: "Keep only the company of believers and let none eat your food except the pious." [Abu Dawood and At-Tirmithi]
Therefore, you should strive to choose pious women whom your husband accept as your friends, and you will surely find righteous and pious women. If you don’t find any righteous women to keep as company, and your husband insists that you do not visit that woman, whom you mention as not being bad but not wearing Hijab, then you are obliged to obey him. Abu Hurayrah narrated that the Prophet said: “If I were to command anyone to prostrate themself before anyone other than Allaah, I would have commanded wives to prostrate themselves before their husbands." [At-Tirmithi]
You may communicate with her through the different means of communication if your husband does not disapprove of it, and you should try to influence her to wear the Hijab.
Allaah Knows best.