Brief Answer:
Yes they are safe to take.

Detailed Answer:
I read your question carefully and I understand your concern.

From what I understand the doctors think that the anxiety and depression are related to vitamin B12 deficiency and are giving escitalopram (Stalopam) to address them as well as correcting the vitamin B12 deficiency by vitamin B12 administration.

If vitamin B12 deficiency has been confirmed through proper tests as I assume it has been done, then it is possible for it to manifest psychiatric symptoms as well (though more commonly other symptoms such as abnormal sensations, balance issues etc). Of course I assume he has been examined for other neurological signs which may speak of other potential causes such as Parkinson's, brain tumor etc. Thyroid dysfunction must have also been considered.

So if that has been done I would say the current management is reasonable. Escitalopram is one of the most common medication for anxiety and depression while vitamin deficiency is corrected through supplements. In terms of safety do not worry they are generally safe with a low rate of side effects. Keep in mind that Stalopam effect takes some weeks to happen, durring the first week at times there is even a temporary worsening of the anxiety.

I remain at your disposal for other questions.

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Brief Answer:
Read below

Detailed Answer:
Thank you for the additional information.

Reference ranges may vary a little among laboratories, but generally those values indicate a deficiency of vitamin D. Vitamin B12 is on the low side but still not below the threshold for deficiency.
While those values are on the low side I wouldn't say they are low enough to justify those manifestations of anxiety, depression and altered thinking, especially as like I said they are not the most common in vitamin b12 deficiency, it is other neurological areas which are affected first. Neither does vitamin D deficiency justify those symptoms.
So if your father has a years long history with these issues perhaps it may be primary depression and a cause may not need to be sought. However if such issues have never been present before and he has been deteriorating only lately some attention must be payed to the possibility of a brain lesion mimicking psychiatric conditions. In that case a neurological exam would be advisable (if not already done that is) and perhaps brain imaging as well.

I hope to have been of help.

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