Hi Mindy,
The executor is responsible for administering the estate. This means that your aunt, as executor (is she the sole executor?) is the only person able to deal with the estate assets until she makes a distribution. Therefore, if the distribution has dragged on for 1.5 years (which is actually not that long a time when it comes to wills and estates), this is not your father's fault.
Administering the estate typically takes longer than 12 months because probate must be granted, assets must be gathered and valued, advertisements for unknown creditors need to be published and the court usually allows 6-12 months to wait for creditors and potential beneficiaries to challenge the will. Distribution should be made only after all these matters are settled. However, 1.5 years may be long for a small estate. If this is the case, your aunt may have been stalling and your father, if he still wants payment (to himself or his children) and your aunt has not dispersed the estate assets, can apply to court for an order to distribute.
Your father cannot refuse a gift as beneficiary without formalities being made (i.e. expressly stating this in a formal letter or in writing). He is still entitled.
If your aunt has dispersed your father's gift, then she will probably have breached her fiduciary duty (owned to your father and other beneficiaries under the will). Your father has a right to (i) have your aunt account for his share of the estate, and (ii) any profits or interest on this share.
Your father will unlikely be able to claim compensation for stress. The law does not punish but rectify positions of parties to what is right. If your father is successful, the judge will award costs. There are a few different types of cost orders the judge may make. The most common is party-party costs. This means that your father will have his fees and expenses reimbursed by your aunt. But the fees and expenses spent must be reasonable. Your aunt may dispute the final bill. If this is the case, the costs will be "taxed" by a "taxation officer". The officer will go through each item on the list, determine if the expenditure was reasonable and if the amount is reasonable. There is a list of "reasonable costs" published by the court against which the officer will refer. This list is very detailed. Typically, your father will receive up to 1/3 of his actual expended costs. Your father's lawyer will be able to explain this more to him.
If your father wants to leave the gift to his children, he will need to first accept the gift himself, then gift it as he likes. This can happen at the same time.