Ferritin 17 (15 - 150) - how much Ferrous Fumerate has been prescribed? It should be one tablet two (or possibly three) times a day. Was she tested for iron deficiency anaemia as well - that would be an iron panel plus full blood count.
She should take each tablet with 1000mg Vit C to aid absorption and help prevent constipation, and take it four hours away from thyroid meds and two hours away from any other medication and supplements as it affects their absorption.
If she is not vegetarian then include liver in her diet once a week, either as a stand alone meal or minced and 'hidden' in casseroles, cottage pie, curry, bolognese, as any other meat dish.
Folate 2.3 (2.5 - 19.5)
Vitamin B12 198 (180 - 900)
Was she tested for Pernicious Anaemia? With folate deficiency plus such a low level of B12 it would have been a good idea. Does she have any signs and symptoms of B12 deficiency - check here b12deficiency.info/signs-an...
I would suggest that you take these results over to the Pernicious Anaemia Society forum here on Health Unlocked for further advice.
Total vitamin D (OH) 24.1 (<25 severe vitamin D deficiency. Patient may need pharmacological preparations)
If she is taking 800iu D3 a day then her level will not rise. She needs a loading dose in accordance with treatment guidelines.
NICE treatment summary cks.nice.org.uk/vitamin-d-d... states:
"For the treatment of vitamin D deficiency, the recommended treatment is based on fixed loading doses of vitamin D (up to a total of about 300,000 international units [IU]) given either as weekly or daily split doses, followed by lifelong maintenance treatment of about 800 IU a day. Higher doses of up to 2000 IU a day, occasionally up to 4000 IU a day, may be used for certain groups of people, for example those with malabsorption disorders.
Several treatment regimens are available, including 50,000 IU once a week for 6 weeks (300,000 IU in total), 20,000 IU twice a week for 7 weeks (280,000 IU in total), or 4000 IU daily for 10 weeks (280,000 IU in total)."
Each Health Authority area has it's own guidelines but they will be very similar. Speak to the GP and insist he treats according to the guidelines.
Or it may be better to do it yourself with better quality supplements bought online and guidance from members here.
Whatever you do, there are important cofactors needed when taking D3 which your GP won't know about because they're not taught nutrition, read -
D3 aids absorption of calcium from food and K2-MK7 directs the calcium to bones and teeth where it is needed and away from arteries and soft tissues where it can be deposited and cause problems.
D3 and K2 are fat soluble so should be taken with the fattiest meal of the day, D3 four hours away from thyroid meds.
Magnesium comes in different forms, check here to see which would suit best and as it's calming it's best taken in the evening, four hours away from thyroid meds -