Can a woman cut her hair before doing ghusl following menses?

There is
nothing wrong with cutting one’s nails or hair before doing ghusl following
menses or afterwards, but a woman should take care, when cutting her hair,
to avoid resembling men or kaafir women. 

The fact
that it is permissible for a woman to cut her hair short is indicated by the
report narrated by Muslim (320) from Abu Salamah ibn ‘Abd al-Rahmaan who
said: The wives of the Prophet (S) used to cut their hair so that it came
down just past their ears. 

al-Nawawi
(may Allaah have mercy on him) said: 

al-Qaadi
‘Iyaad (may Allaah have mercy on him) said: Perhaps the wives of the Prophet
(peace and blessings of Allaah be upon him) did that after the death of
the Prophet (peace and blessings of Allaah be upon him), because they
stopped adorning themselves and they had no need to grow their hair long, so
they reduced the amount of effort required to take care of their hair. What
al-Qaadi ‘Iyaad said about them doing that after his death and not during
his lifetime was also said by others and it is sound. No one should think
that they did that during his lifetime. This indicates that it is
permissible for women to cut their hair, and Allaah knows best. End quote. 

Shaykh Ibn
Baaz (may Allaah have mercy on him) said: We do not know of anything wrong
with women cutting their hair. What is forbidden is shaving the head. You
are not allowed to shave your head, but if you cut it to make it shorter or
reduce its volume, we do not know of anything wrong with that. But that
should be done in a good way that will be pleasing to you and your husband,
and you can agree with him on something that will not be similar to the
hairstyle of kaafir women because leaving it long will entail a lot of work
to wash it and comb it. If the hair is thick and the woman cuts some of it
to make it shorter and reduce its volume, there is nothing wrong with that.
If she cuts some of it for purposes of beautification to make it pleasing to
her and her husband, there is nothing wrong with that. But shaving it
altogether is not permissible except in cases of sickness. And Allaah is the
source of strength. End quote from Fataawa al-Mar’ah al-Muslimah
(2/515). 

Shaykh
Saalih al-Fawzaan (may Allaah preserve him) said: 

It is not
permissible for a woman to cut her hair at the back and leave the sides
long, because this is ugly and messing with her hair which is part of her
beauty, and it is also an imitation of kaafir women. The same applies to
cutting it in different styles with the names of kaafir women or animals,
such as the Diana cut, which is the name of a kaafir woman, or the lion cut
or mouse cut, because it is haraam to imitate kaafir women or animals, and
because this is messing with the woman’s hair which is part of her beauty. 
End quote from Fataawa al-Mar’ah al-Muslimah (2/516, 517). 

And Allaah knows
best.