"Means" doesn't work well, in my opinion. It could be "money" if the trust account contains only cash or close equivalents to cash, or if you only wanted to talk about the monetary value of the account. It would be "assets" if there were diverse assets in the account -- stocks, bonds, etc. -- and you wanted to refer to them rather than to their monetary value.
Edit: you could also use "resources" to refer generally to the purchasing power of the account, its ability to command goods and services.