The 2 years thing is ridiculously long, when most roles have 3 to 6 month probationary periods, and obviously was extended from 1 year for the benefit of employers, not employees.
She should check her contract doesn't link the successful end of probationary period with extended rights, perhaps overriding the minimal statutory rights.
Now in my opinion it is clear the company is operating in bad faith here, and planned to from the beginning. That might not have much legal weight, but hopefully it would have some negotiation weight - shorter notice period, or gardening leave, or 2 days off for reasonable job hunting aspects. These are all reasonable requests. You can hardly be asked to do three months work and be dismissed at the same time. The three months notice is for the employee's benefit, not the employer's.
If they're unreasonable with these, then this is where you know they are being utterly awful, and all good will has gone.
In this case, ignore what they demand (come in 5 days a week for the period, no job hunting, no leave). What are they going to do, sack you? This is the situation where you pull the emergency childcare card ('my income is suddenly at risk, I cannot afford childcare for the summer holidays'), then the stress card, but some jobs do ask if you've been signed off work (is that even legal?). But only if they are utterly unreasonable.
If they are reasonable, then do a work-to-rule handover - some wiki/sharepoint documentation, a couple of handover meetings, best spend time making those process/system diagrams look pretty. Creating training material takes a lot of time, that's why training courses are so expensive. Two hour lunches. Make sure your leaving do is an entire afternoon (your coworkers didn't do this). Maybe say 'everything handed over, i'm available on 07xxxx' with a week or two to go.
The aim is some relaxed months over summer, lunchtime pints in the sun, getting another job lined up for the Monday after your exit date. The last thing you need is stress, because you might have to take time off...
I have been made redundant twice. Once, I demanded they made me redundant after a material change in my working practices they imposed upon me (forcing me to work from home after closing an office, I didn't mind that, but in the end I wanted out and used that). The second time the company found me another role internally very quickly.