At first, meeting Mrs. Moss is like sunshine on a cloudy day. She’s nice, funny, and even gives Richard a discount on his room.
But Richard really can’t catch a break, because "nice" quickly turns into maybe-a-creepy-poisoner-lady. He meets Bess, Mrs. Moss’s daughter, and five hours after he moves in they’re both talking about marriage and inheritance. "Oh, Christ," Richard thinks: "I’ll have to leave this place" (1.11.83).
Or he could just stay forever! Mrs. Moss tells him, "I’d be happy when I died if I thought Bess had a husband like you" (1.11.87). Whoa there, gals: your crazy is showing.
Although we should remember Richard probably has no idea how to respond to people being nice to him. Later on, he decides that actually they’re probably just being nice: "when they thought they had found [good qualities] in one of their race, they instinctively embraced him, liked him, and asked no questions. But such simple unaffected trust flabbergasted me" (1.9.111).
Up until now, there’s been exactly one nice person in his life (Ella) and he barely knew her. Plus, Richard’s mom, who certainly tried her best, would probably never be called "motherly." But "motherly" just happens to be Mrs. Moss’ default state: she is "bland and motherly as always" (1.12.17).
Richard just can’t deal with so much kindness. Like an abused dog, Richard is suspicious of everyone around him. He bites the hands that feed him—or comb his hair.