Women are permitted to combine and shorten namazs during Hac in exactly the same manner as men. There is no distinction between men and women regarding the concessions of combining (jam) and shortening (qasr) namazs during travel and at the specific Hac sites. All scholars agree that the rulings of combining namazs at Arafat and Muzdelife apply equally to women.
At Arafat, all hacilar — men and women — combine Dhuhr and Asr namazs at the time of Dhuhr (jam taqdim), shortening each to two rak'ahs. At Muzdelife, they combine Maghrib and Isha at the time of Isha (jam ta'khir), with Isha shortened to two rak'ahs. Sheikh Ibn Baz confirmed that these concessions are Sunnah and apply to every haci regardless of gender.
Sheikh Ibn Uthaymeen further clarified that women who are traveling for Hac may shorten the four-rak'ah namazs (Dhuhr, Asr, and Isha) to two rak'ahs throughout their journey, just as male travelers do. The shortening applies when they are considered travelers, and the combining applies at the specific Hac locations as part of the Sunnah of Hz. Peygamber. Women who are residents of Mekke shorten at Arafat and Muzdelife due to the Sunnah of the rite, not due to travel.