The possessive form of the plural noun trustees is trustees'.
Trustees is the plural of trustee. "The trustees had no idea where the money went"
The noun 'money' is a singular uncountable noun as a word for currency or coins.The plural noun 'monies' is used almost exclusively in formal business contexts. The noun 'monies' is an uncountable plural noun.The plural possessive form is monies'.Example: The monies' security has been the responsibility of the trustees.
Coaster's is singular possessive. The plural is coasters, the plural possessive is coasters'.
The correct form is "its" for the possessive form in the plural. "Its" is used for both the singular and plural possessive forms, without an apostrophe.
The plural is briefs. The plural possessive is briefs'.
The plural is lads. The plural possessive is lads'.
The plural is trollies. The plural possessive is trollies'.
The plural is stations. The plural possessive is stations'.
The plural is relatives. The plural possessive is relatives'.
Museum is singular. Museum's is singular possessive. Museums is plural. Museums' is plural possessive.
The singular possessive form is heart's; the plural possessive form is hearts'.
The plural form is homes; the plural possessive is homes'.