Section 5. The trustees shall be a corporation for the purpose of taking and holding, by them and their successors, in the name of the commonwealth, and in accordance with the terms thereof, any grant or devise of land or any gift or bequest of money or other personal property made for the use or benefit of the Tewksbury hospital, its patients or former patients, and for the purpose of preserving and investing the proceeds thereof in notes or bonds secured by good and sufficient mortgages or other security, with all the powers necessary to effect said purposes. For said purposes the trustees may employ such agencies as they may from time to time determine to be wise and proper, including any trust company or other corporation authorized by law to administer trusts, and may from funds received as aforesaid or the income thereof pay such expenses as may be necessary for the wise administration of such gifts or trusts, or may delegate any powers conferred by this section upon any such trust company or corporation. In the use, management and administration of such gifts or trusts, the trustees or their agents shall in their discretion so act as most effectively to aid the beneficiaries in accordance with the terms of the gift or trust, and when so acting their judgments and determinations in extending or denying aid or benefit to any individual shall be conclusive and final. No trustee shall be answerable for the use of any money or property received by any beneficiary or for the default or neglect of any co-trustee, or of any agent employed hereunder, or of any corporation to which power is delegated or transferred as herein authorized.