For a woman to perform hajj, she has to be with her husband or any of her male relatives whom she is not permitted to marry because of their close blood relationship (mahram), such as her father, grandfather, sons, grandsons, brothers, nephews and uncles. (See page 207)
However, if a woman performs hajj without a mahram in such a way that she is not exposed to any danger whatsoever, her hajj is valid and would certainly suffice.
