She works as a nurse on the maternity ward and she has some questions about purification and prayer
Question

                (this question is being submitted on behalf of my mother)
We all understand the importance of prayer and offering the prayers at there prescribed times. My question has to do with when someone is working as a nurse. A nurse who works in the maternity ward works with new babies and women on a continuous basis throughout the night. During some of these checks it is very likely that clothes can become spoiled with either urine, blood and other najas due to the reason that it is a maternity ward and children as well as because new mothers need a lot of help (without needing to go into great detail). Understandably when shoes have najas on them we can easily take them off. Following are my questions that pertain to my specific situation:

How would I go about making ablution? do I have to remove my Hijab to make ablution (wudhoo) or can i just lift the hijab and wipe over the front hairs?, do I need to take a change of clothes to make ablution and change my clothes every time I want to offer prayer? I only have a set time for breaks and lunches and sometimes I am unable to pray the prayers on time due to the set breaks and lunches, what should I do about offering prayer on there prescribed times? can they be delayed until break time as long as the break is during the permitted time of the prayer? passed the permitted time of prayer? can I combine prayers?.
Praise be to Allah.
      Firstly: 

    One of the conditions of prayer being valid is the body and 
    clothes being free of impurity. If any impurity (najaasah) gets on to the 
    body or clothes, it is essential to remove it before starting to pray. 

    Your mother can set aside clothes for prayer and clothes for 
    work, then when she wants to pray she could take off the work clothes and 
    put on the other clothes. 

    Or it is enough for her to wash the place where the impurity 
    is on the clothes, then pray wearing them if she wants. 

    Please see the answer to question no.
    12720 and
    125879. 

    Secondly: 

    Wiping the head with water during wudoo’ is one of the 
    obligatory parts of wudoo’. But if a woman is wearing a head cover, she does 
    not have to take it off and she may wipe over it, especially if it is 
    difficult to take it off. Al-Bahooti (may Allah have mercy on him) said: 
    Wiping over a woman’s head cover is valid, especially one that is wrapped 
    around the chin, because Umm Salamah used to wipe over her head cover, as 
    was mentioned by Ibn al-Mundhir, and the Prophet (blessings and peace of 
    Allah be upon him) said: “Wipe over the khuffayn (leather slippers) and the 
    head cover.” Narrated by Ahmad. And because it is a covering that is 
    difficult to remove.

    End quote from Daqaa’iq Ooli al-Nuha, 1/62. See also
    al-Mughni, 1/187 

    The hadeeth “Wipe over the khuffaayn and the head cover” was 
    classed as da‘eef (weak) by Shaykh al-Albaani (may Allah have mercy on him). 
    See Da‘eef al-Jaami‘, no. 1270. 

    Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) was 
    asked: Is it permissible for a woman to wipe over her head cover? 

    He replied: The well-known view of the madhhab of Imam Ahmad 
    is that she may wipe over the head cover if it is wrapped around the chin, 
    because that was narrated from some of the women of the Sahaabah (may Allah 
    be pleased with them). 

    Whatever the case, if there is any difficulty involved, 
    either because it is cold or because it is difficult to take it off and put 
    it on again, that there is nothing wrong with wiping over it in this case, 
    although it is better not to do so.

    End quote from Majmoo‘ Fataawa Ibn ‘Uthaymeen, 
    11/171. 

    Thirdly: 

    The basic principle is that it is not permissible to delay 
    prayer until the time for it is over, except when one has an excuse, because 
    Allah says (interpretation of the meaning): “Verily, As‑Salaah (the 
    prayer) is enjoined on the believers at fixed hours” [al-Nisa’ 4:103]. 
    This has been discussed in the answer to question no.
    21958. 

    What is required of the sister who is asking this question is 
    to take all possible measures to offer the prayers on time. If that is too 
    difficult for her or she is not able to do it because of the way her work is 
    organised, then there is nothing wrong with her putting two prayers 
    together. So she may put Zuhr and ‘Asr together, and put Maghrib and ‘Isha’ 
    together, at the time of the earlier or later prayer, according to what is 
    easiest for her. 

    The scholars of the Standing Committee for Issuing Fatwas 
    were asked: Is it permissible to delay prayer until the time for it has 
    ended, such as ‘Asr prayer, in the case of necessity, namely if a doctor is 
    doing surgery and if he leaves the patient, even for a short time, that will 
    pose a danger to his life? 

    They replied: The doctor who specialises in doing surgery 
    should take care to do surgery at times when he will not miss out on 
    offering the prayers at the proper time. In cases of necessity it is 
    permissible to put two prayers together at the time of the earlier or later 
    prayer, such as putting Zuhr and ‘Asr together, or Maghrib and ‘Isha’, 
    according to what is dictated by necessity. End quote. 

    Fataawa al-Lajnah al-Daa’imah, 
    25/44 

    Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) was asked 
    about the ruling on delaying prayer until the time for it is over because of 
    work, such as a doctor who is on call. 

    He replied: Delaying prayer until the time for it is over 
    because of work is haraam and is not permissible, because Allah says 
    (interpretation of the meaning): “Verily, As‑Salaah (the prayer) is 
    enjoined on the believers at fixed hours” [al-Nisa’ 4:103]. And the 
    Prophet (blessings and peace of Allah be upon him) defined the set times for 
    prayer. So whoever delays the prayer until after these times or does it 
    before these times has transgressed the limits set by Allah, and those who 
    transgress the limits set by Allah are the wrongdoers. So it is not 
    permissible for a person to delay the prayer until the time for it is over 
    for any kind of work. But if the prayer is one that may be put together with 
    the one that comes before it or after it, and it is difficult for him to 
    offer each prayer at its own time, then he may put the prayers together, 
    such as if his shift at work is during the time for Zuhr, and it is too 
    difficult for him to pray Zuhr on time, then he may put it together with 
    ‘Asr prayer, and by the same token he could put ‘Isha’ prayer together with 
    Maghrib, because it is proven in Saheeh Muslim that Ibn ‘Abbaas (may 
    Allah be pleased with him) said: The Messenger of Allah (blessings and peace 
    of Allah be upon him) put Zuhr and ‘Asr, and Maghrib and ‘Isha’, together in 
    Madeenah when there was no state of fear or rain. They asked Ibn ‘Abbaas: 
    What was the purpose behind that? He said: He did not want to make things 
    difficult for his ummah -- i.e., he wanted to avoid making things difficult 
    for them by not putting prayers together. End quote from Majmoo‘ Fataawa 
    Ibn ‘Uthaymeen (12/33). 

    And Allah knows best.