Should she take off her hijaab because her husband tells her to?

Praise be to Allah.

You have to persevere in obeying the command of Allaah and not remove your hijaab, because there is no obedience to any created being if it involves disobedience to the Creator. You should advise him and deal with him kindly and gently, and seek the support of righteous people among your family and his, if it comes to that. We also recommend you read the book "Wasaail Thabat" (Ways to Steadfast Faith) published under the heading Books on this web site. We ask Allaah to help you to be steadfast, and to guide him (your husband).