My mother is 53 years old, when she was 40 years her monthly period started to be irregular it came every few months, in the last 5 years it came only once, just a month ago she started taking HRT tablets (hormone replacement therapy), a week before Ramadan she saw some blood and we think it is caused but the tablets, the blood it is not red but orange/yellow's. She has been like this for the last 12 days and there is no much blood coming it just some discoloring. She would like to know what to do for Ramadan and for her prayers and reading the Qur'an.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

The most prevailing opinion is that there is no given limit to the menopause or the female climacteric. In fact, it comes anytime the menstruation period of the woman stops completely. So, if known menstruation blood comes out after its interruption regardless of the cause, then the blood is considered menstruation blood, i.e. whether it is coming because of treatment or normally.
Ibn Taymiyah was asked about the woman who gets blood following some treatment and had consequently three menstruation periods whether her Iddah is then complete. He replied: 'Yes, when the known menstruation blood comes, it is considered a period and counted in Iddah. Likewise, if she drinks some medicine that interrupts blood or that makes each period more distant from the other. This also is considered a period of cleanness. The same rule applies when she gets angry or tired and has her menstruation; this is counted' .
So, the blood that this woman had is considered menstruation blood unless it is yellowish and its colour is different from the colour of menstruation blood in this case, she is not menstruating.
Allah knows best.