I couldn't tell exactly what it is for based on the photo. Are you a/the trustee for the trust? That means you can determine how the funds are used. It's perfectly logical and legitimate to ask for that information.
Being a trustee simply means managing the items in an estate (money, property, stocks, personal items, etc.) the way the trust directs. If it says for the support of your father then you could limit the dispersal to reasonable items in reasonable amounts for things such as food, shelter, clothes, etc. You may have to be careful that the amounts spent would not affect his federal benefits since trust monies are considered support. In other words, don't put him in a $5000 a month apartment, but you could give him $100 - $200 a month to make up the difference between what the government gives him and a reasonable amount to be spent for his support. Check with Social Security on this, but they may not give you specific information about your father's benefits, just general guidelines.
I'm the trustee for the PR's trust fund. I've only used monies from it for her tuition and a small trip last year. Neither of which affected her eligibility.